Congress’s Power to Investigate Crime Is More Important Than Ever

Editor’s Note: This piece has been adapted from a forthcoming article in the N.Y.U. Journal of Legislation & Public Policy.

With days until the election, it is not hyperbolic to observe that Donald Trump is threatening to weaponize the nation’s justice system in unprecedented ways. He has promised to launch a sweeping campaign of retribution, scuttle criminal investigations, and “impound” funds appropriated by Congress for purposes he opposes. In just the past month, he has threatened to use military forces against American citizens he calls the “enemy from within.”

These threats and others raise grave questions about their legality. Yet the Supreme Court concluded in Trump v. United States that presidents have absolute immunity from criminal prosecution when exercising core powers and presumptive immunity for other official acts. The Court’s opinion has been subjected to bipartisan criticism from scholars, constitutional law experts, judicial luminaries, legal authorities, and pro-democracy organizations.

The implications of this decision will continue to be debated for years, but one consequence is clear: Congress’s power to investigate conduct that may be criminal is now more important than ever. Congress stands as one of the only institutional checks on presidents who commit crimes under broad claims of constitutional immunity.

History of Congress’s Power to Investigate Crime

Can Congress investigate crime? Does it have that authority under the Constitution? In a new article examining the historical evolution of this question over the past century and a half, I conclude that the answer is undoubtedly yes. 

The fact that Congress is investigating “crime” is not a valid basis, by itself, for defying its demands. And ironically, Trump’s unsuccessful litigation to block congressional subpoenas has made this fact clearer than ever in case law.

Debate over this question has a long history. 

For decades, targets—notably including Trump—have argued that the Constitution vests this power only in the executive and judicial branches. This approach, which I refer to as an exclusive separation of powers framework, pits committee investigators against criminal prosecutors in a zero-sum game. Rather than allowing for concurrent investigations, it prioritizes the interests of prosecutors over those of Congress. If targets were to prevail in making this argument, Congress’s investigative authority would be at its weakest point when examining the most treacherous abuses of power. 

At the same time, congressional investigators zealously safeguard their authority to investigate all types of activity, including criminal activity that prosecutors may be investigating at the same time. Under this parallel separation of powers framework, each branch has authority to investigate concurrently, but for different constitutional objectives. Investigations serve as a common means to distinct ends: The legislative branch gathers information to assess problems, craft reforms, and inform the electorate, while prosecutors collect evidence to try, convict, and punish perpetrators.

To help shed light on this recurrent debate, I trace its evolution across three historical periods.

Kilbourn and the Exclusive Framework

The first era centers on a Supreme Court opinion from 1881 known as Kilbourn v. Thompson. That case didn’t involve a criminal proceeding, but a civil bankruptcy. The Court held that Congress could not demand testimony or documents on a matter pending before a bankruptcy court. Since the bankruptcy court was charged with providing remedies, Congress’s investigation “could result in no valid legislation on the subject,” according to the Kilbourn decision. 

The Court also strongly suggested the Framers never envisioned Congress exercising its contempt power—its authority to enforce subpoenas—to inform legislation, but only for so-called judicial functions, such as impeaching federal officials or disciplining its own members. 

Targets of congressional investigations have tried to use Kilbourn to argue that Congress is likewise barred from investigating criminal wrongdoing, claiming law enforcement is the sole province of the executive and judicial branches.

But Kilbourn was flawed from the beginning. As Georgetown Law Professor Josh Chafetz and others have pointed out, Congress easily could have legislated on issues related to the bankruptcy even based on the Court’s narrow recitation of the facts. 

The Court’s account, moreover, was far from complete. Digging into the record, I unearthed surprising new details about Congress’s original investigation that the Court never mentioned: Congress was not just examining a private bankruptcy, but massive corruption across the entire D.C. government, as well as allegations of real estate speculation, dubious public works contracts, and self-dealing involving millions of taxpayer dollars—all valid subjects of legislation. Congress was also examining the potential involvement of executive branch officials and its own members in the scandal, so even under the Court’s faulty logic, it should have sided with Congress. 

These details, not referenced in the opinion and largely forgotten by history, further underscore the weakness of Kilbourn and the exclusive separation of powers framework that rests upon it.

The 20th Century and the Parallel Framework

In the century and a half after Kilbourn was decided, Congress launched sweeping investigations and adopted multiple resolutions making explicit its intent to investigate “criminal” misconduct. And the Supreme Court, in a series of cases including McGrain v. Daugherty, Sinclair v. United States, Adams v. State of Maryland, and Hutcheson v. United States, approved those investigations as serving valid legislative branch purposes. As the Court in Hutcheson stated:

[S]urely a congressional committee which is engaged in a legitimate legislative investigation need not grind to a halt whenever responses to its inquiries might potentially be harmful to a witness in some distinct proceeding ... or when crime or wrongdoing is disclosed.

The Court acknowledged the limitations of Kilbourn’s holding and condemned its previous opinion as “severely discredited.” The Court also held that Congress’ power to enforce subpoenas through contempt is not limited to impeachment or disciplining members, but is inherent in the legislative process itself.

One remnant of Kilbourn worked its way into these new precedents. The Court began to repeat a line Trump would later use in his filings—Congress may not engage in a “law enforcement” purpose. However, my research shows this refrain had little practical effect, as the Court never held that Congress crossed the line from legislative inquiry to criminal prosecution. My review of more than 100 subsequent court decisions revealed no case in which the Supreme Court or any appellate court invalidated any congressional inquiry on that basis.

It’s understandable that prosecutors would prefer to be left alone to do their jobs without congressional committees conducting parallel inquiries that may interfere with their work. Of course, the flip side is true too: Congressional investigators may become frustrated with prosecutors who issue vague, sometimes exaggerated warnings about the potential negative impact of congressional inquiries on future prosecutions. Under the parallel separation of powers framework, they need to accommodate each other’s valid interests.

Richard Ben-Veniste—a former federal prosecutor in the Southern District of New York, assistant special prosecutor with the Watergate Special Prosecution Force, chief minority counsel to the Senate Whitewater Committee, and member of the 9/11 Commission—testified before the Senate Judiciary Committee that there are “no compelling reasons” that congressional and criminal investigations “should not proceed concurrently” and that the “system works best” when committees are “both appropriately aggressive and at the same time thoughtfully deferential to legitimately prosecutorial objectives.”

Working under this parallel framework, concurrent investigations are now common. They’ve included inquiries into Watergate, Whitewater, campaign finance violations, the Sept. 11 terrorist attacks, Blackwater USA, the American mafia and organized crime, the outing of covert CIA operative Valerie Plame, the 2008 financial crisis, the attacks in Benghazi, and many, many others.

One caveat: This analysis focuses primarily on cases in which congressional and criminal investigators are examining the same set of facts involving wrongdoing. It doesn’t resolve the separate and important debate about what happens when Congress trains its focus directly on criminal prosecutors and seeks information about their actions. 

The executive branch has attempted to develop a separate prong of executive privilege to withhold information from Congress about open, and in some cases even closed, criminal cases, and it has relied in part on Kilbourn to support this position. To date, however, no court has endorsed this view or defined the scope of this privilege, so this potential limit on congressional authority remains unresolved.

The Trump Era and Kilbourn’s Fate

The third period I examine is the era of Trump. He launched a relentless but unsuccessful campaign to bring Kilbourn back to life and block Congress from investigating his alleged crimes. He and his aides refused to cooperate with multiple investigations, and they invoked Kilbourn repeatedly in dozens of written filings and oral arguments before courts at all levels—including as a first-line argument before the Supreme Court in Trump v. Mazars. In that case, Trump asked the Court to declare that the House Oversight Committee’s investigation of his finances was off-limits because it involved allegations of criminal activity. Under Attorney General William Barr, the Justice Department even weighed in on their behalf. 

But these efforts never succeeded. Their claims were rejected, disregarded, or ignored every time. 

Take Jan. 6. From its inception, it was evident that Congress would be examining criminal conduct. Live coverage of the mob storming the Capitol as they viciously beat police officers, hunted down lawmakers, and called for the execution of the vice president turned into reports of grave injuries and deaths. As the committee took up its work, the Justice Department and other law enforcement agencies were already conducting their own investigations, and prosecutions eventually climbed into the hundreds. Perhaps more than with any other investigation in U.S. history, it was clear the committee’s work would overlap with ongoing criminal cases.

In response to the committee, Trump and his aides took up the “exclusive” mantle, arguing that Congress had no authority to investigate his alleged crimes. In a suit to block the National Archives from producing documents, he argued that “any investigation into alleged claims of wrongdoing is a quintessential law-enforcement task reserved to the executive and judicial branches” and that “Congress is not a law-enforcement branch of government.” 

The courts rejected this argument. The committee obtained documents from the Archives and other agencies and issued a landmark report after more than 1,000 interviews and depositions and nine public hearings featuring more than 70 witnesses. But at the time, Trump and his allies were pressing the same claim in response to multiple congressional investigations.

In the end, Trump’s insistent, exhaustive, and uniformly unsuccessful legal efforts not only backfired, but created a surfeit of precedents that had the opposite of their intended effect: Instead of bringing Kilbourn back to life, they put to rest lingering doubts about whether Congress is constitutionally authorized to investigate crime.

So did Trump kill Kilbourn? Is it a dead letter?

Not entirely. Although the Supreme Court has criticized the case, it hasn’t formally overruled it. And a few notable holdouts, including Justice Clarence Thomas, still cling to Kilbourn despite its deficiencies. In his Mazars dissent, Thomas called on the majority to overrule the Court’s precedents precisely because those cases “rejected Kilbourn’s reasoning and upheld the power to issue legislative subpoenas as long as they were relevant to a legislative power.” But the Court declined to follow Thomas’s lead. As a result, lower courts have concluded that Kilbourn is now “largely impotent as a guiding constitutional principle.” 

Implications of the Presidential Immunity Decision

If prosecutors can no longer bring certain criminal cases against presidents, does the Court’s logic also bar Congress from investigating that same misconduct? Although Chief Justice John Roberts’s decision is severely problematic in many ways, two key passages suggest Congress is not restricted in the same way as criminal prosecutors. 

First, Roberts notes that the Constitution explicitly charges Congress with investigating presidential crimes through impeachment, which he correctly describes as “a political process by which Congress can remove a President.” 

Second, beyond impeachment, Roberts draws a contrast between criminal prosecution on one hand and demands for information on the other, concluding that presidents are not absolutely immune from the latter. As Roberts explains, “Criminally prosecuting a President for official conduct undoubtedly poses a far greater threat of intrusion on the authority and functions of the Executive Branch than simply seeking evidence in his possession.”

That approach comports with Roberts’s previous opinion in Mazars, which rejected Trump’s claim of absolute privilege in response to congressional document requests and instead established a four-part test to weigh Congress’s interests against those of the president. 

For these reasons, Congress will no doubt continue seeking documents and testimony regarding presidential crimes, including for impeachment and other legislative branch purposes.

There may be concern, especially in a hyperpartisan environment, that some in Congress could abuse their authority. Critics claim this is what Chairman Jim Jordan (R-Ohio)—who defied his own subpoena from the Jan. 6 committee—did when he subpoenaed a former prosecutor from the Manhattan District Attorney’s Office that convicted Trump on 34 felony counts. However, the district court ruled in Jordan’s favor, noting that “[i]t is not the role of the federal judiciary to dictate what legislation Congress may consider or how it should conduct its deliberations in that connection.” To be fair, the court also noted that the subpoenaed witness was a private citizen who was no longer employed by the district attorney’s office and had written a book about his former job.

Congress faces its own risks with irresponsible actions by committee chairs. In addition to negative electoral consequences, such actions can be counterproductive. They can undermine the integrity of a particular committee investigation, encourage defiance by witnesses, and result in public scorn. Worse, they could risk long-term damage to Congress as an institution by emboldening judges to restrict congressional authority in new ways in response to perceived congressional abuses, as demonstrated by the outcome of the Operation Fast and Furious investigation—in which the House Oversight Committee demanded documents from the attorney general.

Finally, safeguarding Congress’s power to investigate crime doesn’t mean targets lack defenses. All targets, including presidents, can assert constitutional privileges, such as the Fifth Amendment. They can argue that a committee has exceeded its mandate from the House or Senate or that questions are not pertinent. Presidents can also assert executive privilege or the Mazars test, and courts will have to balance those claims against Congress’s right to obtain information to serve as a check on the executive branch.

The bottom line, however, is this: Future targets of congressional investigations will stand on extraordinarily weak legal footing if they defy subpoenas based solely on the claim that Congress lacks authority under the Constitution to investigate criminal activity.