With the 2026 midterms approaching, and the prospect of a surge in congressional investigations if the Democrats win a majority in one or both chambers of Congress,² a D.C. Circuit decision issued last month in United States v. Navarro³ provides a timely reminder about this hallmark of congressional investigations—and arguably strengthens legal support for privilege assertions before Congress.

Although this decision does not guarantee protection for privileged materials sought by Congress, it provides more meaningful support for respondents seeking to resist such demands. Parties routinely protect privileged materials and work through these issues in the customary accommodations process. Even so, this legal support is particularly important when responding to Congress in conjunction with parallel investigations. Federal agencies and state regulators may honor privilege assertions while congressional committees maintain discretion to override them. This sometimes forces respondents to navigate conflicting expectations across different government bodies and to deftly navigate unspoken congressional norms and common practices, regardless of the legal framework.

Key Takeaways:

• Congress maintains that common law privileges, including attorney-client privilege, do not limit its constitutional investigative authority—although committees typically honor privilege assertions in practice through an accommodations process.
• Congress asserts that individual committee chairs have discretionary authority to rule on privilege assertions, and no federal appellate court has definitively resolved whether respondents may assert common law privileges against congressional demands.
• The D.C. Circuit's Navarro decision reinforces the Supreme Court's observation in Mazars that subpoena recipients retain common law privileges—persuasive authority that carries weight in the primary forum for congressional subpoena litigation.
• To mitigate waiver concerns, respondents should aim to document the compelled nature of any demands for privileged materials, pursue non-privileged accommodations, maintain strong privilege hygiene around communications and records, and engage counsel with bipartisan congressional experience.

Common Law Privileges and Congress

Among the oldest common law privileges, the attorney-client privilege protects confidential communications between a lawyer and a client made for the purpose of obtaining legal advice. Because the privilege developed through judicial decisions, however, it rests on a different footing than protections guaranteed by the Bill of Rights and enshrined in the Constitution. That distinction matters because Congress’s expansive authority to investigate is implied from the Constitution.⁴

The power to compel information, including through subpoenas, has long been treated as a correlative attribute of the power to legislate. Both chambers have delegated subpoena power to their respective committees and subcommittees.⁵ Federal law also makes compliance with lawful congressional subpoenas essentially mandatory.

Refusal to comply with a valid congressional subpoena can result in congressional contempt proceedings and significant criminal or civil consequences. Under 2 U.S.C. § 192, every person subpoenaed by the House or Senate to give testimony or to produce documents must comply; willful refusal is a misdemeanor referable to the Department of Justice for prosecution. The House may pursue criminal contempt—by referring the matter to the Department of Justice—or civil enforcement of its subpoena in federal court. The Senate has the same two options and may pursue both, though its civil enforcement authority is codified. Upon adoption of a resolution, Senate Legal Counsel may bring a civil enforcement action in the U.S. District Court for the District of Columbia.⁶

In practice, however, congressional investigators typically honor privilege assertions or simply decline to pursue privileged materials. When respondents’ interest in preserving privilege is at issue, investigators weigh the pertinence of the information against whether other means can accommodate the request—such as non-privileged documents or briefings. But Congress has long insisted that it is not bound by judge-made privileges, making this a live issue in some investigations. In fact, both the House and the Senate have rejected proposals that would require committees to recognize common law privileges,⁷ deliberately leaving committee chairs free to rule on privilege assertions as they arise.⁸

The rules of key House and Senate oversight committees also reflect that longstanding institutional position. The Rules of the House Committee on Oversight and Government Reform provide that “[t]he Chair of the Committee has the authority to rule on assertions of privilege,”⁹ without committing the Committee to honor the attorney-client privilege, work product, or any other common law protection. The Rules of Procedure for the Senate Permanent Subcommittee on Investigations are similar: if a deposition witness objects and refuses to testify based on relevance or privilege, Subcommittee Members or staff may seek a ruling from the Chair (or a designated Member), and an overruled witness may be ordered to answer.¹⁰

Congressional committees have also stated this position publicly in recent and historical letters and subpoenas. A July 2026 letter from the House Committee on Science, Space, and Technology to the president of a national scientific organization stated, “[T]he Committee notes that common-law privileges asserted by private entities do not automatically limit Congress’s access to information.”¹¹ That conclusion echoed an August 2021 House Committee on Oversight and Reform letter to the CEO of an application security service company, which stated, “The Committee—under chairs of both parties—does not recognize common law privileges such as attorney-client privilege as a valid reason to withhold documents from Congress.”¹² Similarly, in written instructions accompanying a 2025 subpoena, the House Committee on Oversight and Government Reform stated, “[T]he U.S. House of Representatives and the Committee do not recognize: any purported non-disclosure privileges associated with the common law[.]”¹³

Limited Court Precedent

To date, no federal appellate court has definitively resolved whether a respondent may assert the attorney-client privilege to resist a congressional committee’s demands. Respondents routinely do so in practice, however, and disputes are typically resolved through negotiation rather than litigation. The closest the D.C. Circuit came to addressing the issue was a 2016 dispute in which the Senate Permanent Subcommittee on Investigations subpoenaed documents in a matter involving Backpage.com and its chief executive, who withheld certain materials as privileged.¹⁴ The Subcommittee argued waiver based on the timing of the assertion, the district court ordered production, and the case—which eventually led to a separate criminal prosecution by the Department of Justice—was ultimately dismissed without a ruling on the underlying question.¹⁵

In 2020, Trump v. Mazars¹⁶ marked the first case in which the Supreme Court indicated, contrary to Congress’s long-running assertions, that common law privileges apply in congressional investigations. Writing for a 7-2 majority, Chief Justice Roberts held that the lower courts had not adequately accounted for the separation-of-powers concerns raised by congressional subpoenas for a sitting President’s personal financial records. While describing the limits on Congress’s investigative power, Chief Justice Roberts wrote that recipients of subpoenas “have long been understood to retain common law and constitutional privileges with respect to certain materials, such as attorney-client communications and governmental communications protected by executive privilege.”¹⁷ The opinion cited a Congressional Research Service summary of the Senate Whitewater investigation, during which the Clintons produced notes of a meeting with counsel only after the Special Committee to Investigate Whitewater Development Corporation and Related Matters agreed that disclosure would not waive the privilege.¹⁸

Since then, at least one court considering privilege assertions related to congressional subpoenas adopted a more modest interpretation of Chief Justice Roberts’s language. In Bragg v. Jordan,¹⁹ the Southern District of New York treated the Mazars language as confirming only that a witness may invoke a privilege before a congressional committee, subject to the committee's authority to overrule the assertion. The D.C. Circuit’s recent Navarro decision, however, suggests that appellate courts may be more receptive to the Chief Justice’s view in Mazars.

The Navarro Decision

The Navarro decision arose from investigations conducted by the U.S. House Select Committee to Investigate the January 6th Attack on the United States Capitol. In 2021, after leaving his role as a White House aide during the first Trump Administration, Peter Navarro published a book and gave promotional interviews taking credit for a strategy to delay certification of the 2020 election results. The Select Committee subpoenaed documents and deposition testimony concerning those public statements and the three-volume report Navarro had published as a private citizen. In response, Navarro asserted executive privilege, produced nothing, filed no privilege log, declined to appear for his deposition, and rejected the Committee’s repeated offers to accommodate a privilege claim asserted on a question-by-question basis. The House held him in contempt, a grand jury indicted him on two counts under 2 U.S.C. § 192, and a jury convicted him for contempt of Congress. Navarro completed concurrent four-month sentences in July 2024 while continuing to press his appeal before the D.C. Circuit.²⁰

On July 21, 2026, the D.C. Circuit affirmed Navarro’s conviction in a unanimous opinion. Writing for the panel, Judge Patricia Millett devoted most of the opinion to executive privilege and separation-of-powers arguments. In framing the law governing congressional subpoenas, however, the court stated affirmatively that recipients of congressional subpoenas retain common law and constitutional privileges against governmental demands for disclosure. The decision quoted Chief Justice Roberts’s opinion in Mazars: “Recipients of congressional subpoenas ‘retain common law and constitutional privileges’ against governmental demands for the disclosure of requested information.”²¹ The court then narrowed its focus to the two executive privilege claims at issue—the presidential communications privilege and testimonial immunity. While the relevant language regarding common law and constitutional privileges is technically dicta, this statement in the D.C. Circuit’s decision signals that at least one appellate court is aligned with Chief Justice Roberts’s observation in Mazars.

The Navarro decision language is noteworthy for respondents to congressional subpoenas for several reasons. First, although technically dicta, the D.C. Circuit’s statements provide further persuasive authority alongside Mazars—and language from the D.C. Circuit carries substantial weight given that it is the primary forum for litigation over congressional subpoenas and executive privilege. Second, Navarro extends the pattern Mazars began. Both the Supreme Court and the D.C. Circuit have now suggested that recipients of congressional subpoenas retain their common law privileges, consistent with the practical approach respondents and counsel have taken for years. Notably, neither Navarro nor Mazars addressed Congress’s contrary interpretation. Regardless of which party holds a majority in the House or the Senate following the midterms, targets of congressional investigations can now point to this additional language when necessary in efforts to protect information covered by the attorney-client privilege and other common law privileges—even as they continue to work through the normal accommodations process.

Preparing for Investigations

Ultimately, Navarro does not alter the legal and strategic predicament confronting congressional oversight respondents. Nor does it change customary practice and norms. There are still no definitive rulings on the merits from any court, despite the dicta in both Navarro and Mazars. And both cases focused principally on separation-of-powers issues, which are not typically present when Congress subpoenas private companies and individuals. Congressional investigators on both sides of the aisle will still take the position that they are not bound by attorney-client privilege assertions, and respondents will continue to pursue a wide variety of accommodations to preserve privilege.

Respondents facing a committee subpoena should assume that investigators will evaluate privilege assertions under their committee’s own rubric—often based on internal, behind-the-scenes precedent—and should plan accordingly. To protect materials from broader waiver arguments, respondents should document the compelled nature of Congress’s demands for privileged materials and build a record when privilege becomes an issue, reflecting the understanding that such materials remain protected if sought by parties other than Congress (and routinely, by Congress itself in the accommodations process). Interestingly, at least one D.C. Bar ethics opinion suggests that defense counsel in congressional investigations have “a professional responsibility to seek to quash or limit the subpoena on all available, legitimate grounds.”²² Limitation and accommodation is the usual course, rather than motions to quash, but this guidance is worth bearing in mind. And maintaining strong hygiene around communications and company records—such as by clearly identifying privileged content and documenting the basis for privilege—remains critically important for protecting confidential legal advice. Consulting counsel with deep bipartisan experience navigating congressional oversight is another prudent step for any company preparing for or facing potential or actual investigations.