Introduction Committee investigations in the House of Representatives can serve several objectives. Most often, an investigation seeks to gather information either to review past legislation or develop future legislation, or to enable a committee to conduct oversight of another branch of government. These inquiries may be called legislative investigations because their legal authority derives implicitly from the House's general legislative power. Much more rarely, House committee investigations have been carried out to determine whether there are grounds to impeach a federal officialâa form of inquiry known as an impeachment investigation. An impeachment investigation has typically been one of the House's first steps in the exercise of its constitutional impeachment power, and may conclude with the investigating committee recommending articles of impeachment to the full House. While the labels "legislative investigation" and "impeachment investigation" provide some context to the objective or purpose of a House inquiry, investigations may not always fall neatly into one of these categories. To the contrary, distinguishing between legislative and impeachment investigations might sometimes be difficult, especially when an investigation focuses on alleged misconduct by an official subject to impeachment by the House. This ambiguity is reflected in the various ongoing House committee investigations concerning President Trump. On September 24, 2019, Speaker Pelosi announced that these investigations constitute an "official impeachment inquiry." While these committee investigations into allegations of presidential misconduct are proceeding, in the words of the Speaker, under the "umbrella of [an] impeachment inquiry," most appear to blend legislation, oversight, and impeachment purposes. However labeled, many of the House investigations have been hindered by refusals to comply with committee subpoenas for documents or testimony. Various legal explanations have been provided for these refusals, including that federal law prohibits the disclosure of grand jury materials to Congress, that the relevant committee subpoenas lack a required legislative purpose, and that the information sought is protected by executive privilege. These interbranch disputes over information access have raised interest in whether invocation of the impeachment power will improve the House's ability to acquire withheld information. This report addresses that question, with a focus on presidential impeachment investigations. Specifically, the report considers whether the impeachment power may strengthen the House's investigative authorities in a manner that would improve the chamber's ability to obtain information, especially through the courts. Compared to a typical legislative investigation, an impeachment investigation may be more likely to acquire certain categories of information, including grand jury materials, documents and testimony related to either the President's exercise of his exclusive constitutional powers or his conduct occurring prior to taking office, and communications covered by executive privilege. But Congress's right of access to relevant information in a more typical legislative investigation is also substantial. Thus, partly because the line between legislative and impeachment investigations is sometimes blurred, but primarily because both impeachment and legislative investigations constitute an exercise of significant constitutional power, House committees may have adequate authority and tools to obtain much of the information they seek regardless of whether they are engaged in a legislative investigation or one relying on the impeachment power. What Is an Impeachment Investigation? The Constitution provides the House with the "sole Power of Impeachment," but neither that document, federal statutes, nor House Rules define impeachment investigations. Nor have the courts asserted "any role" in addressing the impeachment power generally or impeachment investigations specifically. In fact, the Rules of Proceeding and Speech or Debate Clauses of the Constitution, along with political question doctrine, all generally prevent the courts from "questioning Congress about actions taken in the impeachment process." The manner by which the House chooses to implement its impeachment powers appears therefore to be textually and historically committed to the discretion of the House. The House, however, has adopted no explicit definition of what constitutes an impeachment investigation. Left with gleaning a definition from the various constitutional provisions governing impeachment and the House's historical practiceâwhich includes 19 impeachments (15 of which were federal judges) arising from over 90 past impeachment investigations âan impeachment investigation may be defined as an investigation carried out to aid the House in its "constitutional responsibility" of determining whether "sufficient grounds" exist to charge an impeachable official ("[t]he President, Vice President and all civil Officers of the United States" ) with an impeachable offense ("[t]reason, Bribery, or other high Crimes and Misdemeanors" ). Nor has the House established a single, uniform approach to starting impeachment investigations. Instead, the process has evolved, generally along with changes to the House's committee structure and the investigative authorities with which those committees have been vested. Although impeachment investigations have often been authorized by a resolution of the House, there have also been impeachment investigations conducted (and articles of impeachment recommended by the Judiciary Committee and approved by the House) without an explicit authorization. For example, the House explicitly directed the Judiciary Committee to "investigate fully and completely whether sufficient grounds exist for the House" to impeach President Clinton, but in the1980s provided no authorization for investigations into allegations of impeachable conduct against Judges Walter Nixon, Alcee Hastings, and Harry E. Claiborne, who were ultimately impeached by the House. There are still other examples in which a resolution of authorization was provided only after a committee had engaged in a "preliminary" impeachment investigation. For example, although the House eventually authorized the impeachment investigation of President Nixon, the Judiciary Committee began the "preliminary phases of an inquiry into possible impeachment" months earlier. The somewhat inconsistent House practice on the use of authorizing resolutions may be due to any number of practical, procedural, or political factors. For example, at least until the second half of the 20th century, an authorizing resolution from the House was often a practical necessity for an effective impeachment investigation. This is because in the period before standing committees existed an investigating committee needed to be created and authorized. Even after standing committees were established, the House typically still needed to provide the committee with both investigative jurisdiction and compulsory investigative tools such as the power to issue a subpoena to force the disclosure of information. Indeed, although the House often adopted resolutions providing individual committees with limited subpoena powers following the Legislative Reorganization Act of 1946, it was not until 1975 that the House granted its committees standing investigative and subpoena powers under House Rules. Even after 1975, there was still practical value in authorizing resolutions, which typically provided the investigating committee with additional investigative tools beyond what the committee may have otherwise possessed, such as the ability to conduct staff depositions or issue written interrogatories. Thus, for a good portion of the House's history, authorizing resolutions were generally needed to give a committee the tools necessary to carry out an effective and expeditious investigation. Use of an authorizing resolution has also provided the House with the opportunity to assert control over the scope, direction, and conduct of a committee's impeachment investigation. The House, Its Committees, and the Delegation of Investigative Powers Along with the practical explanations discussed above, it is also possible that the different approaches to initiating impeachment investigations reflect different conceptions of the House's impeachment power and the derivative authority that may be conferred to its committees to carry out investigations ancillary to that power. The nature of this power is perhaps best explored in relation to the House's well-established authority to conduct legislative investigations. These investigations are carried out under the House's implied constitutional authority to investigate in "aid of the legislative function." While there are various "legislative functions" that an investigation may fulfill, the prototypical legislative investigation of the executive branch is carried out so that Congress can either inform itself for purposes of lawmaking or conduct oversight of those charged with the "faithful" execution of the law. This familiar exercise of investigative power, though not explicitly enumerated in the Constitution, is so essential to the functioning of a legislature as to be implicit in the "legislative powers" vested in Congress by Article I, Â§1 of the Constitution. These investigations play a vital role in the constitutional system, as they are intimately and directly tied to Congress's power to legislate. Because "a legislative body cannot legislate wisely or effectively in the absence of information respecting the conditions which the legislation is intended to affect or change," impairment of Congress's authority to gather information leads to the impairment of Congress's core function of legislating. The necessity and importance of legislative investigations are also reflected in the statutory requirement that all committees "exercise continuous watchfulness" over the executive branch's implementation of law and the directive under House Rule X that standing committees "review and study on a continuing basis" the administration of law, the operation of agencies, and "any conditions or circumstances that may indicate the necessity or desirability of" new legislation. House Rules further provide that committees have "general oversight responsibilities" that are generally to be used "to assist the House in its" legislative tasks. To carry out these requirements, the House has extensively delegated investigative powers and tools to its committees to aid the chamber in its traditional legislative functions. Under House Rules, a standing House committee may conduct "such investigations and studies as it considers necessary or appropriate in the exercise of its responsibilities"; hold hearings; take staff depositions; and "require, by subpoena â¦ the attendance and testimony of such witnesses and the production of such â¦ records â¦ as it considers necessary." But by the terms of the delegation, and because committees are creatures of their parent chamber, use of the provided compulsory investigative tools extends only to "subjects within the jurisdiction of a committee" and "for the purposes of carrying" out any of its enumerated "functions and duties." The precise constitutional source (or sources) for impeachment investigations, and the subsequent delegation of investigatory impeachment authority to House committees, is less clear. It would appear that the legal basis for these investigations could be viewed in various waysâwith each interpretation leading to slightly different roles for both the House and any investigating committee. First, impeachment investigations could be seen as another form of the traditional legislative investigation. Rather than assisting the House for the purpose of lawmaking or oversight, the investigation is made to "aid" the House in a different "legislative function" âimpeachment. Under this conception, the House holds one broad-based power of inquiry, and if any distinction between legislative and impeachment investigations exists, it is not one of constitutional source of authority, but one based on purpose. If impeachment investigations are an extension of the House's traditional power of inquiry, and therefore derive from the same source as legislative investigations, it would appear that a committee would be free to use its existing investigative authorities, within the jurisdiction delegated to the committee, to assist the House in carrying out the function of impeachment. Under this view, no additional authorization or delegation from the House would be necessary to conduct an impeachment investigation (though it may be desirable if the House wished to either guide the investigation in a specific direction or provide a committee with additional authorities). But it could also be argued that impeachment investigations derive their authority not from the general legislative power, but directly and independently from the House's "sole Power of Impeachment" in Article I, Â§ 2 of the Constitution. The U.S. Court of Appeals for the District of Columbia Circuit (D.C. Circuit), for example, has suggested in dicta that the Impeachment Clause is the "express constitutional source" for the "investigative authority" of an "inquiry into presidential impeachment." Although investigations are not explicitly mentioned in Article I, Â§ 2, or any of the other impeachment-related clauses, the power to impeach must by necessity include the power to investigate allegations of impeachable conduct. Under this conception, the authority to investigate for impeachment is either implicit in the impeachment power itself, or "necessary and proper to carrying into execution" that power, but in either case is a power that is constitutionally independent of Congress's general power to conduct legislative investigations. If impeachment investigations derive their authority not from the general legislative power, but independently from the House's exclusive impeachment power, it has been argued that some form of additional authorization or delegation may then generally be necessary to transfer that power from the House to its committees since current House Rules are "silent on the issue of impeachment." Committees are "representatives of the parent assembly" and have only the power to inquire into matters that are within the scope of the authority delegated to them by the House. It is that delegation, whether in the form of a free-standing resolution or under House Rules, that is "the controlling charter of the committee's powers." Thus, under the independent power conception, it could be argued that if a committee is going to exercise impeachment powers provided "sole[ly]" to the House, including the "investigative powers that are ancillary" to impeachment, it needs to do so with some adequate authorization or delegation from the Houseâa delegation that the current House Rules have not explicitly made. The argument does not appear to be that the Constitution's impeachment provisions directly require authorization of an impeachment investigation, but rather that as a matter of House Rules and the established relationship between the House and its committees, a House committee can exercise the investigative powers of impeachment only if that authority has been delegated to it by the parent body. Whatever the merits of this interpretation, it would appear to be in tension with those House precedents in which impeachment investigations were undertaken without House authorization, and in conflict with the House General Counsel's current litigating position in multiple cases. In sum, there is neither a clear definition in law or House Rules of what constitutes an impeachment investigation, nor a clearly established House process for how such an investigation is to be initiated. As a result, it would appear that the House has many choices in how it executes an impeachment investigation. House leadership appears to take the view that a specific authorization of an impeachment inquiry is not constitutionally necessary for committees to engage in an impeachment investigation of the President. On the other hand, some might argue that adopting an authorizing resolution is required orâeven if not legally necessaryâuseful because it provides the House with the opportunity to empower and direct a committee's impeachment investigation, while also providing a clear and forceful imprimatur of the House's support for that inquiry. The Question of Authorization in the Current House Impeachment Inquiry In the House's ongoing investigations of President Trump, no committee has received the type of explicit and direct authorization ultimately provided in the Clinton and Nixon investigations. Nevertheless, even if one were to accept for purposes of argument that authorization is a prerequisite to a committee engaging in an impeachment investigation, it could be argued that the House recently provided this authorization, at least for wielding the powers of impeachment in court. In June, the House adopted H.Res. 430 , which provides that "in connection with any judicial proceeding â¦ the chair of any standing or permanent select committee exercising authority thereunder has any and all necessary authority under Article I of the Constitution." The accompanying Rules Committee report cites the Judiciary Committee's investigation into whether to recommend articles of impeachment to the House as an "example of a Committee being able to use 'all necessary authority under Article I of the Constitution.'" The White House, however, asserts that House committees are not currently engaged in an impeachment investigation absent a formal authorizing resolution from the House. But there would likely be significant challenges to pursuing this argument in litigation, particularly given the courts' historical reluctance to scrutinize the House's implementation of its own internal powers. Indeed, whether a committee is engaged in an impeachment investigation represents the unique convergence of various areas in which courts are generally reluctant to second-guess the position of the House and its committees, including the House's implementation of its "sole Power of impeachment"; the House's exclusive authority to set and interpret its own rules; and a committee's role in articulating the purpose of an investigation. According to at least one commentator, it seems likely that to obtain judicial recognition of an impeachment investigation the House need only present enough evidence to "persuade the court that its current investigation is sufficiently tied to the impeachment process." While this deferential approach to actions of the House and its committees is not absoluteâfor example, courts sometimes have exercised their judicial powers to ensure that the committee is acting within the scope of the authority delegated to it by the parent chamber âit may be reinforced in the current situation because the House General Counsel (HGC) has asserted that there is "no authority for the proposition that the House must vote to authorize the Committee to investigate impeachment." The HGC's position is important because it is overseen by the Bipartisan Legal Advocacy Group, which "articulates the institutional position of the House in all litigation matters." The D.C. Circuit has suggested that when the HGC voices an interpretation of internal House matters it must be "given great weight." That said, an explicit authorization from the House could remove any ambiguity as to the appropriate characterization of the committee investigations. But in many ways, the current focus on whether the House must authorize an impeachment investigation may lead to the misimpression that an impeachment inquiry is the only means by which Congress may investigate and acquire information concerning allegations of executive branch wrongdoing. A committee can investigate executive branch misconduct in an impeachment investigation, a legislative investigation, or some combination of both. Investigations conducted pursuant to the impeachment power may, as discussed below, provide the House with some access advantages, perhaps most significantly if executive privilege is invoked as a justification to deny congressional access to information. But an executive official, including the President, may also be the subject of a legislative investigation, and Congress's ability to access information from the executive branch in these investigations is oftentimes substantial. Accordingly, the degree to which Congress may obtain information through an impeachment inquiry that it cannot acquire in a traditional legislative investigation may not always be as significant as might first appear. Even without invocation of the impeachment power, House committees retain existing authority to investigate allegations of executive branch misconduct, including criminal activity as part of a legislative investigation. Courts have generally recognized that the power to conduct legislative investigations includes the authority to inquire into and investigate the conduct of government officials, especially when a committee is considering possible remedial legislation. As one district court recently stated, even absent any claim that an investigation is being undertaken for purposes of impeachment, committee investigations into misconduct by executive branch officials generally fit "comfortably within the broad scope of Congress's investigative powers" so long as the investigation is within the committee's jurisdiction and is carried out for a legislative purpose. Opinions of the Supreme Court reinforce this notion by holding that Congress's implied investigative power, wholly apart from impeachment, "comprehends probes into departments of the Federal Government to expose corruption, inefficiency or waste," and includes the authority to "inquire into and publicize corruption, maladministration or inefficiency in agencies of the Government." Thus, the line between an impeachment investigation and a legislative investigation into official misconduct may not only be significantly blurred, but in some instances, may also be unnecessary to draw given the tools and authority available to committees to conduct legislative investigations into executive branch misconduct. This authority includes not only the use of compulsory investigative tools like the subpoena, but also other forms of legislative leverage generally available to the House, its committees, and even individual Members. Impeachment Investigations: Scope of Access to Information Addressing the scope of the House's access to information during an impeachment inquiry requires some brief comparison of impeachment and legislative investigations. To begin, the two types of investigations have much in common: both represent exercises of the House's constitutional power; both act as essential checks on executive overreach and help ensure preservation of the separation of powers; and both are unique and consequential powers characterized by their mix of judicial, legislative, and political features. In addition, whether engaged in an impeachment or legislative investigation, the tools used to gather information are now mostly the same, especially given recent changes to the House Rules that provide committees with authority to carry out investigations in an increasingly prompt manner and without the full participation of the committee. In any investigation, a committee would likely obtain most information through requests for information, voluntary interviews, hearings, subpoenas for documents or testimony, and depositions. But the two investigations arguably contrast in a few notable ways. For example, the frequency with which each is exercised differs greatly. While the House has conducted myriad legislative investigations of the executive branch, there have been comparatively few impeachment investigations of executive branch officials. In addition, the House has previously granted the subject of an impeachment investigation certain procedural rights that are not seen in legislative investigations. For example, during both the Nixon and Clinton impeachment investigations, the House Judiciary Committee adopted resolutions affording the President and his counsel the right to respond to evidence gathered by the committee, raise objections to testimony, and cross-examine witnesses, among others. In another distinguishing feature, the Judiciary Committee's power to issue subpoenas in impeachment investigations has previously been altered in an effort to encourage "a fair, impartial and bipartisan" investigation. In both the Nixon and Clinton investigations, the power to subpoena was provided to "the chairman and the ranking minority member acting jointly, or, if either declines to act, by the other acting alone...." Even so, "[i]n the event either [the Chair or the Ranking Member] so declines," the provisions continued, "either shall have the right to refer to the committee for decision the question whether such authority shall be so exercised â¦" Thus, in the case that the Chairman and the Ranking Member disagreed on issuing a subpoena, the question would be settled by vote of the Judiciary Committee. The functioning of the provision was described by some Members of the Judiciary Committee as "practically nullif[ying] any truly independent subpoena power for the ranking minority member â¦," as the Chairman's position would likely be upheld by the committee. Significantly, there may be some ways in which the House's investigative authority is either amplified or broadened during an impeachment investigation. The precise extent of any legal advantage, however, is not entirely clear. While there is a reservoir of historicalâand to a much more limited extent judicialâprecedents that can be used to analyze the House's authority to obtain information from the executive branch in traditional legislative investigations, the same cannot be said for impeachment investigations. There have been relatively few impeachment investigations of executive branch officials, and none that have been presented to the courts for resolution of constitutional questions of information access. Despite the limited historical precedent, early statements from all three branches support the House's robust and expansive right of access to information pertinent to an impeachment investigation. Since nearly its inception, the House has viewed its impeachment power as including "the right of inquiry â¦ to the fullest and most unlimited extent," and "certainly impl[ying] a right to inspect every paper and transaction in any department." Neither the executive nor judicial branches, the House has asserted, can "seek to impede the House in the exercise of its sole power to impeach." And while the Supreme Court has little to no role in reviewing the impeachment power generally, it has compared the House's right to information in an impeachment investigation to that of a court of law, stating that the House may obtain information "in the same manner and by the use of the same means, that courts of justice can in like cases." As one district court has stated about presidential impeachment investigations, [I]t should not be forgotten that we deal in a matter of the most critical moment to the Nation, an impeachment investigation involving the President of the United States. It would be difficult to conceive of a more compelling need than that of this country for an unswervingly fair inquiry based on all the pertinent information. The executive branch appears to have similarly acknowledged the breadth of impeachment investigations, although usually in the context of denying Congress's right of access in a legislative investigation. In an oft-quoted example, President James K. Polk stated that the authority of the House in an impeachment investigation "would penetrate into the most secret recesses of the Executive Department" and would include the authority to "command the attendance of any and every agent of the Government, and compel them to produce all papers, public or private, official or unofficial, and to testify on oath to all facts within their knowledge." "If the House of Representatives, as the grand inquest of the nation â¦ should think proper to institute an inquiry," Polk continued, "every facility in the power of the Executive [would] be afforded to enable them to prosecute the investigation." The need for the House to obtain access to relevant information in an impeachment investigation may also be underscored by the essential role impeachment plays in ensuring presidential accountability. For instance, given the Department of Justice's (DOJ's) position that a sitting President is not subject to indictment or criminal prosecution while in office, impeachment and removal may be one of the few available mechanisms to hold a President immediately accountable for criminal conduct. Broad access to evidence either supporting or refuting allegations of presidential misconduct could be seen as essential if the House is to exercise its "right of accusing" and if the impeachment power is to maintain its envisioned role as an "essential check" on the executive branch generally and the President specifically. While these statements and principles establish a general proposition that the House enjoys broad access to information in an impeachment investigation, this access may be subject to certain constitutional limitations that generally attach to congressional investigative activity. For example, provisions of the Bill of Rights that have been found to apply in legislative investigations, including the First Amendment, Fourth Amendment, and the Fifth Amendment's privilege against self-incrimination, may also apply in impeachment investigations. Other constitutional principles that may limit committee access to information in legislative investigations, for example considerations arising from the separation of powers such as executive privilege, may prove less of an obstacle and apply with less strength in an impeachment investigation. Potential Investigative Advantages of an Impeachment Investigation When examining the legal implications of impeachment investigations, and especially whether an investigation may strengthen the House's hand in any information access dispute with the executive branch, it may help to think of interbranch investigative conflicts as proceeding in two, sometimes overlapping, phases: a political phase and (in limited situations) a judicial phase. This staged approach offers a useful analytical framework for assessing the impact an impeachment investigation may have on decision making in all three branches of government. Impact of the Impeachment Power on the Political Stage of an Investigative Conflict The first phase of an investigative dispute between Congress and the executive branch is typically political in nature, in that conflicts that may arise are generally steered by political forces, with outcomes dependent upon not only each branch's evaluation of the costs and benefits of a given position, but also each branch's willingness and ability to exert either direct or indirect pressure on the other. This phase is typically characterized by a process of negotiation and accommodation, whichâthough often guided by legal considerations âis also influenced by the use of various levers of political or institutional influence. For Congress, these levers are manifold, and include, among other tools, threatened and actual restrictions on appropriations, changes to delegated executive branch authority, delay of nominations, and attempted enforcement of subpoenas through mechanisms such as criminal contempt of Congress. For the executive branch, leverage lies mainly in the fact that it possesses the information Congress seeks, and therefore delays or a continuation of the status quo may work in its favor. The vast majority of information access disputes are resolved at this political stage, typically either by the executive branch agreeing to comply with congressional demands, Congress relinquishing its request, Congress agreeing to narrow its inquiry, or through a settlement or information access agreement in which Congress is provided access under certain restrictions. Because of the nature of interbranch negotiations, and the paucity of impeachments of executive branch officials, it is difficult to assess the impact an impeachment investigation would have on the political phase of an interbranch dispute. Even so, the significance of a possible exercise of the impeachment power, along with a possible resulting increase in political and public pressure, may itself affect the executive's compliance decisions. During the Nixon impeachment investigation, the House Judiciary Committee noted that "not one" subject of the nearly 70 prior impeachment investigations "challenged the power of the committee conducting the impeachment investigation to compel the production of evidence it deemed necessary." President Andrew Johnson, for example, voluntarily provided the Judiciary Committee with sensitive information during that committee's impeachment investigationâincluding confidential communications with advisers and information related to the use of his pardon and veto power. Presidents Nixon and Clinton also pledged cooperation with House impeachment investigations. But an impeachment investigation is not a panacea for access. Both Nixon and Clinton were later viewed by the Judiciary Committee as withholding relevant evidence. President Nixon ultimately refused to comply with numerous committee subpoenas, and President Clinton was accused of either refusing to comply with requests for written admissions or providing the Committee with false or misleading responses. The Judiciary Committee's response to the actions of President Nixon and President Clinton displays another tool of leverage that uniquely attaches to an impeachment investigation: the threat that noncompliance with committee demands for information could rapidly lead to the adoption of an article of impeachment for contempt of Congress. In a legislative investigation, the tools available to a committee to seek enforcement of a demand made to the executive branch are limited. The primary current avenue for forcing compliance with a subpoena appears to be through the judiciary in a civil enforcement action. The Senate Watergate Committee, which was engaged in a legislative investigation, pursued this avenue of enforcement when President Nixon refused to comply with that committee's subpoenas for White House tapes. The House Judiciary Committee, on the other hand, chose not to litigate enforcement of its subpoenas during its impeachment investigation of President Nixon, concluding that it would be "inappropriate to seek the aid of the courts" because the Framers had made clearâby vesting the impeachment power "solely" in the Houseâthat there was not "any role for the courts in the impeachment process." Instead, the Committee obtained portions of the information it needed from other sources (including the Watergate special prosecutor and grand jury) and recommended to the House an article of impeachment based on President Nixon's failure to comply with the Committee's subpoenas. The Judiciary Committee took the same approach during the Clinton impeachment, approving and recommending to the House an article of impeachment based on the President's "refusing and failing to respond to certain written requests for admission" and for providing incomplete or "false and misleading" information to the Committee. Knowledge that a committee engaged in an impeachment investigation is poised to recommend an independent article of impeachment for failure to comply with a committee subpoena might serve as a tool of leverage during negotiations in the political phase. Impact of the Impeachment Power at the Judicial Stage of an Investigative Conflict If there is an impasse at the political phase, either the House, or in very limited circumstances the executive branch, may transition the investigation into the judicial stage by asking the federal judiciary to decide the ongoing disagreement. Because political negotiations tend to continue, resolution of the dispute at this stage may occur either as a result of political accommodations undertaken by political actors, or as a result of the application of legal principles by federal judges. Such cases usually require the courts to consider both the scope of Congress's investigatory power and any legal restrictions or privileges invoked by the executive branch. The involvement of the courts in information access disputes between the legislative and executive branches has been historically rare, but appears to have become more common in recent years, at least with respect to disagreements over House subpoenas. The traditional preference for political rather than judicial solutions seems supported by the fact that neither Congress nor the President appears to have turned to the courts to resolve an investigative dispute until the 1970s. But it is not only the political branches that have been wary of judicially declared outcomes. The courts themselves have also generally sought to avoid adjudicating investigative disputes between the executive and legislative branches, instead encouraging settlement of their differences through a political resolution.0F Consistent with that approach, lower federal courts have suggested that judicial intervention in investigative disputes "should be delayed until all possibilities for settlement have been exhausted." The courts have never resolved an interbranch subpoena dispute in an impeachment investigation. As noted, there are many reasons for this, including the infrequent occasions in which such disputes arise, the fact that the Speech or Debate clause and the political question doctrine appear constitutionally to prevent judicial review of most aspects of the impeachment power, and because the House itself has suggested that seeking judicial involvement in an impeachment investigation is inappropriate. Moreover, because impeachment is an internal House process, any exercise of the power is typically intertwined with the House's authority to set its own rules, an authority courts are reluctant to disrupt or second-guess. Thus, some evidence suggests that both the House and the courts have viewed judicial involvement in an impeachment inquiry as inappropriate or in excess of the judiciary's power. As such, any discussion of the legal impact an impeachment investigation may have on the judicial stage of an investigation is necessarily speculative. If the House were to seek judicial enforcement of a subpoena issued as part of an impeachment investigation, questions surrounding the courts' role may increase the complexity of the case. To be sure, the courts have made clear that, when necessary, they have the authority to adjudicate subpoena enforcement cases. But to the extent a court views an investigative conflict that arises during an impeachment investigation as constituting "judicial review" of the impeachment power, it could feel obligated to leave resolution of the dispute to the political branches. During the Nixon impeachment investigation, the House Judiciary Committee noted that its "determination not to seek to involve the judiciary reflected not only an intent to preserve the constitutional structure, but also the high probability that the courts would decline to rule on the merits of the case because it is nonjusticiable" under the political question doctrine. Were the court to reach this conclusion it would cut off, at least in an impeachment investigation, one of the House's principal legal mechanisms of enforcing subpoenas issued to the executive branch. In such a scenario, the House might need to find other methods of compelling compliance with its investigative demands, including perhaps through the impeachment power itself. Nevertheless, if the House took a dispute to court, and the court was willing to hear it, there appear to be at least three potential ways in which an impeachment investigation could, relative to a legislative investigation, provide the House with a stronger legal position in any attempt to use the judiciary to obtain information. All three are applicable to the current House investigations into the conduct of President Trump. An impeachment investigation may (1) improve the likelihood of a court authorizing committee access to grand jury materials; (2) relieve any possible limitations imposed by the requirement that a committee act with a "legislative purpose"; and (3) improve the likelihood that a committee will be able to overcome claims of executive privilege made in response to congressional demands. However, it is important to note that even in these areas, it is arguable that a congressional committee engaged in a legislative investigation could also obtain much of the same information, as both legislative and impeachment investigations constitute an exercise of significant constitutional authority. As a result, while an impeachment investigation may very well increase the House's access to information, House committees may have substantial authority to obtain a significant amount of information without reliance on the impeachment power. Access To Grand Jury Materials One area of ongoing dispute between the House and the Trump Administration is congressional access to grand jury materials. House investigations have thus far been unsuccessful in obtaining evidence and materials gathered by the grand jury empaneled for use in Special Counsel Robert Mueller's investigation of Russian interference in the 2016 election and possible obstruction of justice by President Trump. DOJ has asserted that the secrecy requirements of Rule 6(e) of the Federal Rules of Criminal Procedure prevent such a disclosure. Past precedents, however, suggest that a court would likely accord a committee engaged in an impeachment investigation access to grand jury materials. Rule 6(e) establishes a general requirement of grand jury secrecy. Under the Rule, identified persons (including attorneys for the government and grand jurors) may not disclose "a matter occurring before the grand jury" unless the disclosure fits within certain enumerated exceptions, many of which require court approval. Although there is no clear definition of what constitutes a "matter occurring before the grand jury," the rule has generally been interpreted as broadly encompassing anything that might reveal what took place in the grand jury room. None of the exceptions in Rule 6(e) explicitly permit disclosure of grand jury material to Congress in the course of an investigation. But courts have previously provided Congress with access to these materials on various grounds. Disclosure has primarily been approved to a committee engaged in an impeachment investigation through the Rule's exception permitting release of protected materials "preliminary to or in connection with a judicial proceeding." In these cases, courts appear to have viewed an impeachment trial in the Senate as a "judicial proceeding" and the impeachment investigation in the House as "preliminary" to that "judicial" trial. As summarized by a federal district court, "There can be little doubt that an impeachment trial by the Senate is a 'judicial proceeding' in every significant sense and that a House investigation preliminary to impeachment is within the scope of the Rule." These conclusions are further informed by two court opinions determining that committee legislative investigations do not meet the requirements of the judicial proceeding exception, including one in which a committee requested grand jury materials to "fulfill its oversight responsibilities." Notably however, the legislative investigations did not involve an individual official's misconduct or raise impeachment issues. Grand jury materials were disclosed to Congress during both the Nixon and Clinton impeachment inquiries, though there is ambiguity as to the legal reasoning applied by the courts in authorizing those disclosures. During the Nixon impeachment investigation, the House Judiciary Committee requested access to evidence and materials that had been presented to the court by the grand jury. Judge John Sirica of the U.S. District Court for the District of Columbia concluded that disclosure to the Committee was "eminently proper, and indeed obligatory," but his opinion did not include a detailed discussion of Rule 6(e). Judge Sirica appears to have relied on various factors in reaching his decision, including a belief that courts should "presumptively favor disclosure to those for whom the matter is a proper concern and whose need is not disputed"; the fact that the President did not object to the release; and the desire to avoid the "incredible" conclusion that "grand jury matters should lawfully be available to disbarment committees and police disciplinary investigations and yet be unavailable to the House of Representatives in a proceeding of so great import as an impeachment investigation." The D.C. Circuit affirmed in Haldeman v. Sirica by expressing "general agreement" with Judge Sirica's opinion. But it too identified no single or clear reason for permitting disclosure. Despite neither Judge Sirica's district court opinion nor the D.C. Circuit's opinion in Haldeman making any explicit holding as to impeachment and Rule 6(e)'s judicial proceeding clause, a recent D.C. Circuit decision stated that "we read Haldeman ... as fitting within the Rule 6 exception for 'judicial proceedings.' Doing so reads the case to cohere, rather than conflict, with the Supreme Court and D.C. Circuit precedents...." The D.C. Circuit also authorized Independent Counsel Ken Starr to provide the Judiciary Committee with grand jury material in connection to the Clinton impeachment. The reasoning of the judicial order, which occurred before the House had formally authorized the impeachment investigation, was perhaps even more opaque than in the earlier cases interpreting Rule 6(e)'s application to the Nixon impeachment investigation. However, the judicial order in the Clinton case appears to have been influenced by now-expired statutory requirements included in the Independent Counsel Statute (Act). Upon a motion from Starr, the Special Division of the D.C. Circuit (responsible for overseeing the jurisdiction of Independent Counsels) authorized Starr to "deliver to the House of Representatives" material he found necessary to comply with the Act's explicit requirement that he advise the House of "any substantial and credible information which such independent counsel receives â¦ that may constitute grounds for an impeachment." Although not providing any analysis, the D.C. Circuit stated that "[t]his authorization constitutes an order for purposes of" the judicial proceeding provision of Rule 6(e). While there is precedent supporting the conclusion that a committee engaged in an impeachment investigation can obtain grand jury materials, there are also ways in which a committee engaged in a legislative investigation may be able to obtain that same information. For example, two courts have authorized disclosure of grand jury materials during a legislative investigation based on a determination that Congress has a "constitutionally independent legal right" to obtain information in furtherance of "legitimate legislative activity" that either overrides Rule 6(e) or requires that the rule be interpreted in a way that does not apply its nondisclosure requirements to legitimate investigative requests of Congress. For example, in In re Grand Jury Investigation of Ven-Fuel , a Florida federal district court held that a congressional subcommittee engaged in "legitimate legislative activity" was entitled to grand jury information because it had "demonstrated [a] constitutionally independent legal right to the documents" sought. The decision was based on the court's reading of the Speech or Debate Clause, which the court interpreted as providing "the inherent, implied power to conduct legislative activity" including investigations, and upon a desire to "avert and minimize" constitutional conflict between the branches. While V en - Fuel has been subject to some judicial criticism for its interpretation of the Speech or Debate Clause, the opinion nevertheless supports the proposition that a committee engaged in legitimate legislative investigative activity has a right of access to grand jury material despite Rule 6(e). As such, while Congress is most likely to obtain access to grand jury materials as part of an impeachment investigation, there are arguments that a committee can potentially gain access to such material as part of a traditional legislative investigation. Implications for Legislative Purpose The Trump Administration has argued that some of the ongoing House investigations, especially those focusing on the President's conduct before taking office, lack a "legislative purpose" and therefore exceed the committees' investigative authority. Those arguments have thus far been rejected by the three courts that have reached the merits of the question (two district courts and the D.C. Circuit). Nevertheless, the legislative purpose requirement appears to be substantially limited as a defense to a subpoena in an impeachment investigation. As noted, Congress enjoys broad constitutional authority to obtain information relevant to its legislative investigations. But because that authority is derived from the Constitution's delegation of legislative power to Congress, it extends only to those inquiries that can be said to "aid the legislative function." The Supreme Court has generally implemented this constitutional limit on the scope of the investigative power by requiring that committee investigations serve a valid "legislative purpose." The legislative purpose requirement is quite generous, permitting investigations into any topic upon which legislation could be had or over which Congress may properly exercise authority, including investigations undertaken by Congress to inform itself for purposes of lawmaking or possibly to ensure that the executive branch is complying with its obligation to faithfully execute laws passed by Congress. In practice, the legislative purpose requirement rarely acts as a significant restriction on legislative investigations, especially those relating to government officials. This is principally because the scope of what constitutes a permissible legislative purpose is broad and because courts have effectively adopted a presumption that committees act with a valid purpose. But the courts have acknowledged at least two general types of investigations in which Congress likely exceeds its authority. First, Congress does not act with a legislative purpose when investigating private conduct that has no nexus to the legislative function. As summarized by the Supreme Court, a committee "cannot constitutionally inquire 'into the private affairs of individuals who hold no office under the government' when the investigation 'could result in no valid legislation on the subject to which the inquiry referred.'" Second, the Supreme Court has stated that Congress does not act with a legislative purpose when the subject of an investigation is a function "exclusively" committed to another branch of government. As stated in Barenblatt v. United States : "[l]acking the judicial power given to the Judiciary, [Congress] cannot inquire into matters that are exclusively the concern of the Judiciary. Neither can it supplant the Executive in what exclusively belongs to the Executive." The D.C. Circuit recently reaffirmed this restriction, holding that when "no constitutional statute may be enacted on a subject matter, then that subject is off-limits to congressional investigators." The legislative purpose requirement would appear to impose few, if any, consequential restrictions on a committee impeachment investigation. But the manner in which the requirement applies to an impeachment inquiry may depend upon whether the source of authority for such an inquiry is thought to derive from the House's general legislative power or from the Constitution's specific provisions concerning impeachment. If an impeachment investigation derives from Article I's vesting of legislative power in the House and Senate, then the legislative purpose requirement would likely apply as it does to other investigations conducted pursuant to that power. The requirement, however, would appear to be easily satisfied in an impeachment investigation because the legislative function and purpose that is being served is clear: the committee is assisting the House in carrying out its impeachment power. If, on the other hand, the authority for an impeachment investigation does not arise from Article I's vesting of "legislative powers" in a Congress, but instead derives directly and independently from the House's impeachment power, it need not be exercised in "aid of the legislative function," and, as a result, the legislative purpose restriction would not apply. Regardless of how the requirement relates to impeachment, it would appear that the scope of an impeachment investigation is principally governed not by the need for a "legislative purpose," but instead by its relationship to the House's impeachment role. As such, the permissible scope of an impeachment investigation is initially narrow, in that the investigation would presumably need to relate to the House's role in determining whether an impeachable official has committed an impeachable offense. But once an investigation meets that threshold requirement, the scope of the investigation is broad, to potentially include any matter "reasonably relevant" to the possible impeachment. While the legislative purpose requirement is unlikely to impose any substantial restriction on the scope of an impeachment investigation, both the previously discussed Supreme Court case law and more recent decisions from two federal district courts and the D.C. Circuit suggest that the requirement plays a similarly narrow role in legislative investigations focusing on presidential misconduct. For example, both the D.C. federal district court and the D.C. Circuit recently rejected an attempt by President Trump to block his accounting firm from complying with a House Oversight and Reform Committee subpoena for the President's financial records on the ground that the Committee lacked a legislative purpose. In holding that the Committee had authority to seek the financial documents as part of its ongoing legislative investigation, the district court explicitly noted that "Congress plainly views itself as having sweeping authority to investigate illegal conduct of a President," even "before initiating impeachment proceedings." The court was not willing to adopt an interpretation of legislative purpose in legislative investigations that would "roll back the tide of history" regarding congressional investigations of the President. The D.C. Circuit affirmed in Trump v. Mazars USA, LLP , holding in a 2-1 decision that the Committee's subpoena was a valid exercise of the Committee's authority to conduct legislative investigations. In doing so, the court made two key holdings as to the proper application of the legislative purpose requirement, both of which support committee authority to investigate presidential misconduct as part of a legislative investigation. First, the court held that the Committee had articulated "strong evidence" of its legitimate legislative purpose by asserting that the subpoenaed information was needed to "review multiple laws and legislative proposals," including legislation pending before the House. The fact that one of the Committee's purposes was to investigate potential criminal wrongdoing or misconduct by the President did not undermine the committee's legitimate purposes as "an interest in past illegality can be wholly consistent with an intent to enact remedial legislation." Indeed, a committee's "interest in alleged misconduct" can be "in direct furtherance of its legislative purpose." Second, the court held that the subject of the Committee investigation was one "on which legislation may be had." The court evaluated legislation that would require the presidential disclosure of financial information as the appropriate "category of statutes" that could result from the committee investigation. Applying separation-of-powers principles to that general class of statute, the court could "detect no inherent constitutional flaw in laws requiring Presidents to publicly disclose certain financial information." The dissenting judge in Mazars would have concluded that "[i]investigations of impeachable offenses simply are not, and never have been, within Congress's legislative power" because "impeachment provides the exclusive mechanism for Congress to investigate such conduct." In response to this "novel" position, the majority opinion engaged in some limited discussion of the relationship between legislative and impeachment investigations. That discussion was characterized by deference to Congress. As the court noted, the Constitution leaves questions of "whether to commence the impeachment process" and when to "move from legislative investigation to impeachment" to Congress's "judgment." Moreover, Congress, and not the courts, must make the "quintessentially legislative" determination of whether misconduct is "better addressed" through "oversight and legislation" or through the "grave and weighty process of impeachment." In sum, the legislative purpose requirement is unlikely to be construed as posing an obstacle to information access in an impeachment investigation. Nor does the requirement appear to serve as a consequential legal limitation on legislative investigations, including those focusing on executive branch misconduct, so long as a committee can articulate a connection to a "subject on which legislation may be had." Overcoming Claims of Executive Privilege Executive privilege has been formally asserted as a justification for noncompliance with committee subpoenas in the ongoing House investigations. As discussed, a court may be hesitant to resolve a conflict between a congressional committee and the President over executive privilegeâinstead preferring that the political branches negotiate a resolution or that Congress enforce its demands by use of its own legislative and impeachment powers. However, if a court were to address a privilege dispute, including one over subpoenaed documents or testimony by executive officials, there are reasons to believe that a committee engaged in an impeachment investigation may be more likely to overcome a presidential assertion of the privilege than a committee engaged in a traditional legislative investigation. Even still, a committee engaged in a legislative investigation, depending on the "nature and appropriateness" of the committee's function and its need for the information, may also be able to access certain material covered by the privilege. Executive privilege is a term that has been used to describe the President's power to "resist disclosure of information the confidentiality of which [is] crucial to fulfillment of the unique role and responsibilities of the executive branch of our government." However, there is not one, single "executive privilege." Instead, there is a suite of distinct privileges, each of differentâthough sometimes overlappingâscope. These privileges primarily include the presidential communications privilege, which generally protects communications involving the President or his close advisers that relate to presidential decisions; the deliberative process privilege, which generally protects predecisional and deliberative communications made within the executive branch; and, at least under the executive branch's view, the law enforcement privilege, which arguably protects the contents of open (and sometimes closed) law enforcement files, including evidence gathered in an investigation and communications related to investigative and prosecutorial decisionmaking. In a congressional investigation, the precise privilege asserted in response to a subpoena is an important determination because each component privilege arises from a different source of law, with some components more firmly established in judicial precedent than others. For example, while the Supreme Court has recognized that the presidential communications privilege derives from the Constitution, the deliberative process privilege appears to arise principally from the common law, but, at least in the view of one district court, may have a "constitutional dimension." On the other hand, although the executive branch asserts that the law enforcement privilege derives from both the President's powers under Article II and constitutionally based individual trial and privacy rights, those arguments have not been directly tested in courtâat least not in the context of a congressional subpoena where committees have previously objected to that privilege's use. What is apparent is that none of the executive privileges, even if found to cover subpoenaed information, necessarily presents an absolute bar to congressional access. As announced by the Supreme Court in United States v. Nixon , when faced with an executive privilege dispute courts must "resolve [the] competing interests in a manner that preserves the essential functions of each branch." When the showing of need is adequate, the privilege is overcome. For example, in Nixon , the Court held that the President's "generalized interest in confidentiality â¦ must yield to the demonstrated, specific need for evidence in a pending criminal trial...." As such, it would appear that the type of privilege at play, the corresponding executive need for confidentiality, and Congress's interest in obtaining the information all may impact potential judicial outcomes in an executive privilege dispute. The Supreme Court has never addressed executive privilege's application in either a legislative or impeachment investigation. In fact, the leading (and arguably only substantive appellate) case addressing any component of executive privilege in the congressional context is the D.C. Circuit's decision in Senate Select Committee v. Nixon . That case involved an effort by the Senate Watergate Committee to enforce a subpoena issued to President Nixon for recordings of specific conversations he had with presidential advisers in the Oval Office, thus squarely implicating the presidential communications privilege. Notably, the subpoena was issued as part of a legislative, rather than impeachment, investigation. Although ultimately siding with the President, the D.C. Circuit made clear that a President's assertion of executive privilege could be overcome by a "strong showing of need by another institution of government â¦" As applied to Congress in the exercise of its investigative powers, this meant that a committee may overcome the President's privilege when it has shown that "the subpoenaed evidence is demonstrably critical to the responsible fulfillment of the Committee's function." The Senate Watergate Committee sought to make the required showing by asserting it had a "critical" need for the tapes to carry out the two functions that most frequently form the basis of a legislative investigation: oversight and lawmaking. First, pursuant to its oversight function, the Committee argued that access to the tapes was necessary to "oversee the operations of the executive branch, to investigate instances of possible corruption and malfeasance in office, and to expose the results of its investigations to public view." Second, pursuant to its lawmaking function, the Committee argued that "resolution, on the basis of the subpoenaed tapes, of the conflicts in the testimony before it 'would aid in a determination whether legislative involvement in political campaigns is necessary.'" The circuit court rejected both arguments, holding that the Senate Watergate Committee's need was "too attenuated and too tangential to its functions to permit a judicial judgment that the President is required to comply with the Committee's subpoenas." That holding, however, appears to have been based on a pair of unique facts: copies of the tapes had been provided to the House Judiciary Committee under that Committee's impeachment investigation and the President had publicly released partial transcripts of the subpoenaed conversations. Both of these disclosures significantly impacted the appellate court's assessment of the Senate Watergate Committee's need for the tapes. For example, because the House Judiciary Committee had already obtained the tapes, any further oversight need by the Watergate Committee was "merely cumulative." With regard to the Watergate Committee's lawmaking functions, the D.C. Circuit held that the particular content of the conversations was not essential to future legislation, as "legislative judgments normally depend more on the predicted consequences of proposed legislative actions ... than on precise reconstruction of past events." Any "specific legislative decisions" faced by the Committee, the court concluded, could "responsibly be made" based on the released transcripts. There was some suggestion in Senate Select that the case may have been resolved differently if the committee seeking the tapes had been engaged in an impeachment investigation. This line of reasoning was developed in the decision below, where the district court, after holding that the President was not obligated to comply with the Watergate Committee's subpoena, noted that "Congressional demands, if they be forthcoming, for tapes in furtherance of the more juridical constitutional process of impeachment would present wholly different considerations." On appeal in Senate Select , the D.C. Circuit also drew a somewhat similar comparison between the Senate Watergate Committee's oversight function and the House Judiciary Committee's impeachment function. The court did not, however, make any clear statement as to how it would weigh one relative to the other. Instead it stated that we need neither deny that the Congress may have, quite apart from its legislative responsibilities, a general oversight power, nor explore what the lawful reach of that power might be under the Committee's constituent resolution. Since passage of that resolution, the House Committee on the Judiciary has begun an inquiry into presidential impeachment. The investigative authority of the Judiciary Committee with respect to presidential conduct has an express constitutional source. The Supreme Court made a similar suggestion nearly a century earlier in Kilbourn v. Thompson , reasoning in dicta that while the House in that case lacked a valid legislative purpose to compel testimony, if an investigatory purpose "had been avowed to impeach ..., the whole aspect of the case would have been changed." These general statements suggest that courts may treat impeachment investigations differently from legislative investigations, but they do not elaborate on how or why. Although not directly articulated by the courts, there appears to be a variety of reasons an impeachment investigation might be balanced against an invocation of executive privilege in a manner that is more favorable to congressional access. First, it is arguable that the importance of the impeachment function's constitutional role in addressing misconduct by federal officials and preserving the separation of powers requires that impeachment investigations be afforded the utmost deference when weighed against executive branch confidentiality interests. Indeed, there is substantial support for the proposition that executive privilege simply cannot be used to refuse Congress access to relevant information in an impeachment investigation. As previously discussed, Congress has long viewed its power to obtain information in furtherance of its impeachment power to reach "the fullest and most unlimited extent." In its report on the Nixon impeachment investigation, the House Judiciary Committee adopted this argument, concluding that [w]hatever the limits of legislative power in other contextsâand whatever need may otherwise exist for preserving the confidentiality of Presidential conversationsâin the context of an impeachment proceeding the balance was struck in favor of the power of inquiry when the impeachment provision was written into the Constitution. Because the House's need for information in an impeachment investigation has been equated to that of a court in a judicial proceeding, it is possible to analogize the situation to that considered by the Supreme Court in United States v. Nixon , where the Court weighed the privilege in the context of a criminal trial subpoena. It could be argued that as in response to a subpoena in a pending criminal proceeding, a court could similarly view the privilege as insufficient to withstand a subpoena in an impeachment investigation. As articulated by the Judiciary Committee, "[i]f a generalized Presidential interest in confidentiality cannot prevail over 'the fundamental demand of due process of law in the fair administration of justice,' neither can it be permitted to prevail over the fundamental need to obtain all the relevant facts in the impeachment process." This position is buttressed by concerns expressed by all three branches that executive privilege should not be used to hide wrongdoing, which would form the core of any impeachment investigation. Second, courts have suggested that the frequency with which disclosure may occur in a particular context is an important factor in any executive privilege balancing. For example in Nixon , the Supreme Court reasoned that "we cannot conclude that advisers will be moved to temper the candor of their remarks by the infrequent occasions of disclosure because of the possibility that such conversations will be called for in the context of a criminal prosecution." Similar reasoning was applied in Dellums v Powell , in which the D.C. Circuit held that an executive privilege claim by former President Nixon was overcome in a civil suit alleging a civil conspiracy among high-level federal officials to deny a group of citizens their constitutional rights. There, the circuit court held that "the possibility of disclosure" in such a limited class of cases "is not unlike the possibility of disclosure in criminal casesâthe infrequent occasions of such disclosure militate against any substantial fear that the candor of Presidential advisers will be imperiled." This line of reasoning suggests that a court may be more willing to order disclosure to a committee engaged in a historically rare impeachment investigation than it would to a committee in a much more common legislative investigation. Finally, the need for specific factual evidence in an impeachment investigation may be greater than in a legislative investigation. In Senate Select , the court suggested that specific information was not always necessary for Congress to carry out its lawmaking tasks. In doing so, the court distinguished the role of a legislative investigation from that of a grand jury investigation: There is a clear difference between Congress's legislative tasks and the responsibility of a grand jury, or any institution engaged in like functions. While fact-finding by a legislative committee is undeniably a part of its task, legislative judgments normally depend more on the predicted consequences of proposed legislative actions and their political acceptability, than on precise reconstruction of past events; Congress frequently legislates on the basis of conflicting information provided in its hearings. In contrast, the responsibility of the grand jury turns entirely on its ability to determine whether there is probable cause to believe that certain named individuals did or did not commit specific crimes â¦ We see no comparable need in the legislative process, at least not in the circumstances of this case. Impeachment investigations (and impeachment decisions), on the other hand, might require a more exacting factual record. A decision to impeach is not a typical generalized legislative determination, but is perhaps more aptly characterized as a specific finding that the evidence suggests wrongdoing adequate to support the impeachment of a federal official. Impeachment is assuredly a weighty legislative interest, and long-standing visions of the power suggest that a committee engaged in an impeachment investigation may be more likely to overcome the President's privilege than a committee engaged in a legislative investigation. Nevertheless, it remains the case that in certain circumstances, a committee engaged in a legislative investigation may also obtain information protected by executive privilege. History provides numerous examples of the executive branch voluntarily disclosing information to Congress that it initially identified as protected. Moreover, Senate Select cannot be read as establishing that legislative investigations can never overcome claims of executive privilege. As was stated by the Watergate Committee, "the court's decision rested, as the court observed, on 'the peculiar circumstances of this case,' and should not necessarily prevent legislative committees in the future from obtaining materials relating to presidential communications." Instead, it would appear that a committee engaged in a legislative investigation can itself overcome a claim of executive privilege so long as it can show that "the subpoenaed evidence is demonstrably critical to the responsible fulfillment of the Committee's function." Conclusion An impeachment investigation is a substantial exercise of constitutional power vested exclusively in the House of Representatives. Invocation of the power likely strengthens the House's existing investigative authorities in ways that may allow the House (through its committees) to obtain more information from the executive branch than might otherwise be received through more traditional legislative investigations. Even so, reliance on the impeachment power may not always be necessary for Congress to obtain sensitive categories of information, including grand jury materials, evidence of private misconduct, or information protected by executive privilege. Whether investigating to inform itself for purposes of legislating, to conduct oversight of the executive branch, or to determine whether there is adequate reason to impeach a federal official, the House has broad authority to access relevant and needed information.