Come January, a Congress newly dominated by Democrats will launch vigorous investigations of the Trump administration and its allies.

Lawmakers will face a target-rich environment, one that includes crypto deals, pardons, extrajudicial killings on the high seas, a Justice Department-led retribution campaign against the president’s political opponents and the gift of a Qatari jet.

But they will also face hurdles and roadblocks — erected by the Supreme Court.

In the court’s 2024 decision granting President Donald Trump substantial immunity from prosecution, Chief Justice John Roberts indicated that some subjects may be entirely off-limits to congressional investigators.

“Congress cannot act on, and courts cannot examine, the president’s actions on subjects within his ‘conclusive and preclusive’ constitutional authority,” the chief justice wrote. Those subjects included issuing pardons, firing subordinates and deciding “which crimes to investigate and prosecute.”

The immunity decision “has quietly weakened Congress’s ability to conduct legislative oversight over the executive branch,” David Manners-Weber wrote on the Lawfare blog just before the midterm elections.

Does Congress Have Standing to Sue?

Whatever the subjects of congressional investigations, the administration is unlikely to give Congress documents or let officials testify, a clash that could lead to lawsuits. And it is not at all clear that the Supreme Court would be willing to mediate those disputes or if the justices would side with the Democratic Congress if it does.

Perhaps surprisingly, the court has never definitively resolved a basic question: Can Congress sue the executive branch?

In 2015, Justice Ruth Bader Ginsburg noted in passing that “whether Congress has standing to bring a suit against the president” was an open question. “A suit between Congress and the president,” she observed, “would raise separation-of-powers concerns.”

Lower courts have been more receptive to suits from legislators.

In a pair of decisions in 2020, in the waning days of the first Trump administration, the D.C. Circuit ruled that lawsuits could proceed despite objections to the lawmakers’ standing.

In one decision, the court said that the House Judiciary Committee, then led by Democrats, had standing to sue Don McGahn, a former White House counsel, to compel him to testify. In the other, the court allowed the full House of Representatives to sue over Trump’s use of emergency powers to spend more public funds on a border wall than Congress had appropriated.

McGahn and the committee settled their dispute following some additional twists and turns. After the 2020 election, the Biden administration stopped building the border wall, then asked the Supreme Court to wipe out the appeals court’s decision.

The Biden administration, aware of political pendulum swings, sided with the Trump administration and argued that the House alone should not be allowed to sue the president.

Elizabeth Prelogar, the solicitor general under President Joe Biden, told the justices that letting the House sue “would inject the federal courts into fundamentally political disputes and upset the balance of power between the political branches.”

The Supreme Court granted the Biden administration’s petition and vacated the D.C. Circuit’s decision as moot. The court’s brief order said nothing about whether Congress, or parts of it, had standing to sue the executive branch.

I asked Payvand Ahdout, a law professor at the University of Virginia and an authority on interbranch litigation, for an overview of the likely litigation.

“I largely agree that there are many roadblocks to courts rendering decisions on the merits in any of these cases,” she said in an email. “And even if Congress can overcome those roadblocks, courts frequently engage in avoidance techniques to keep from ordering a coordinate branch of government to take action.”

But she added that “the judiciary is not a monolith,” and “we may see some cases where Congress finds an ally in the lower courts that moves the needle for investigations and oversight.”

Subpoenas to Private Parties

So far, I’ve been discussing clashes between Congress and the executive branch. Lawmakers will probably find it easier to obtain information from private parties like Elon Musk or the law firms that settled with the administration after threats that they and their clients could lose government contracts.

But even in those kinds of cases, the court has imposed limits on the authority of lawmakers. In 2020, in Trump v. Mazars, the court considered congressional subpoenas seeking Trump’s tax and business records from accounting and financial institutions with which he had done business. Trump sued to block the release of the records.

Returning the case to a lower court for further analysis, Roberts stressed that lawmakers needed “a valid legislative purpose” for seeking the records.

“Congress may not issue a subpoena for the purpose of ‘law enforcement,’” he wrote, quoting an earlier decision, “because ‘those powers are assigned under our Constitution to the executive and the judiciary.’”

The ruling was not particularly clear about where to draw the line between the two. In general, the chief justice seemed to prefer accommodation over litigation.

“Historically, disputes over congressional demands for presidential documents have not ended up in court,” he wrote. “Instead, they have been hashed out in the ‘hurly-burly, the give-and-take of the political process between the legislative and the executive.’”

That is, he urged the parties to work out their differences and leave the courts out of it.

The quotation supporting that approach was part of 1975 testimony from a Justice Department lawyer before a Senate committee. The lawyer was Antonin Scalia, who would join the Supreme Court about a decade later.

In the Trump era, the give-and-take Scalia called for seems to have vanished.

The administration has, for instance, taken an extraordinarily broad view of executive privilege, saying it extends to the president’s discussions with people outside the government.

In August, the Office of Legal Counsel, the unit of the Justice Department that advises the executive branch on the law, issued a memorandum making the case for a vast expansion of the scope of executive privilege. It relied heavily on the Mazars decision from 2020, citing it eight times.

—

This article originally appeared in The New York Times.

By Adam Liptak/Doug Mills
c. 2026 The New York Times Company