WASHINGTON — The House Judiciary Committee on Friday said it was asking a federal judge to unseal grand jury secrets related to Robert S. Mueller III’s investigation, saying it would use the court filing to make the most explicit declaration yet that lawmakers are weighing whether to impeach President Trump.
In a significant escalation, Representative Jerrold Nadler of New York, the Democratic chairman of the committee, said at a news conference that the application to the court will declare that the panel needs access to Mr. Mueller’s grand-jury evidence — such as witness testimony — to decide whether to recommend articles of impeachment against the president.
“Because Department of Justice policies will not allow prosecution of a sitting president, the United States House of Representatives is the only institution of the federal government that can now hold President Trump accountable for these actions,” Mr. Nadler quoted the legal filing as telling the judge, Beryl A. Howell, who supervised Mr. Mueller’s grand jury.
Referring to the part in the Constitution that gives Congress the power to impeach and remove a president, the application continues, he said: “To do so, the House must have access to all the relevant facts and consider whether to exercise all its full Article I powers, including a constitutional power of the utmost gravity — recommendation of articles of impeachment.”
Still, his account of the pending filing, which he said would be filed Friday afternoon, stopped short of explicitly declaring that it has formally opened an impeachment inquiry.
The long-awaited filing comes two days after Mr. Mueller testified before Congress for the first time about the findings of his 22-month investigation into Russian election interference and possible obstruction of justice by Mr. Trump. Now Democrats who control the panel are seeking to add more evidence to the trove of information they are collecting about the case.
Mr. Mueller’s report showed the Trump campaign welcomed illegal assistance from the Russians in 2016 and expected to benefit from it, but investigators did not establish that he had conspired with them in the illegal hacking and dumping of Democratic emails. It also explored several episodes in which Mr. Trump tried to impede the investigation.
But the special counsel decided not to render judgment about whether Mr. Trump should be charged with obstruction of justice, citing a Justice Department view that sitting presidents are temporarily immune from indictment while they are in office.
Democrats have been divided about whether the House should formally declare that the committee is conducting an impeachment inquiry — a step that launched the proceedings against both presidents subjected to such proceedings in the modern era, Richard Nixon and Bill Clinton.
More than 90 House Democrats have said they support opening such proceedings, including Representative Ann McLane Kuster of New Hampshire on Friday, and some Democrats see such a step as a moral imperative to leave a black mark on Mr. Trump’s historical record, even if Senate Republicans are unlikely to remove him.
Others fear it could provoke a backlash, firing up Mr. Trump’s supporters and endangering newly elected Democrats who won moderate districts in the 2018 midterm.
Speaker Nancy Pelosi has pressed caution.
“We will proceed when we have what we need to proceed,” the speaker told reporters on Friday, when asked if she was trying to run out the clock on impeachment. “Not one day sooner.”
Against that backdrop, some Democratic staff members and lawmakers have been arguing that it is unnecessary to gain the full chamber’s approval to launch an inquiry, in part because the Judiciary Committee chairman has already gained the power to issue subpoenas and take depositions — authorities that earlier impeachment inquiry resolutions had granted.
The Judiciary Committee has been flirting with the topic of impeachment for months, subpoenaing witnesses and holding hearings designed to better understand Mr. Trump’s behavior and potentially develop charges against him. In a hearing focused on Mr. Mueller’s report earlier this month, Mr. Nadler said that “articles of impeachment are under consideration as part of the committee’s investigation, although no final determination has been made.”
By formally declaring that the panel is doing that in a court filing, Democrats are trying to get past the internal debate without forcing members from moderate districts to vote on whether to do so. Ms. Pelosi approved the language in the lawsuit, according to a person familiar with its drafting.
The specific information at issue in the court filing are the portions in the Mueller report that were redacted because the information fell under a rule in the federal criminal code that makes information presented to a grand jury secret. That rule has only limited exceptions to share it with outsiders. Democrats want the House to gain access to the redacted portions of the report, as well as the underlying transcripts and documents that Mr. Mueller used a grand jury to gather.
In 1974, the Watergate prosecutor, Leon Jaworski, and his grand jury obtained a judge’s permission to send the evidence they had gathered to the House Judiciary Committee, which was already formally conducting an impeachment inquiry into Nixon. In that case, the Nixon Justice Department did not object to letting lawmakers see the materials.
In the current case, the committee is trying to get the material on its own. Attorney General William P. Barr has declined requests by Mr. Nadler that the Justice Department join the committee in petitioning the court to share the information.
One complication is that the Court of Appeals for the District of Columbia recently issued a ruling with a narrow view of when courts may let outsiders see grand jury information. It limited the criteria to an explicit list of exceptions contained in the Federal Rules of Criminal Procedure, saying courts have no inherent authority to make other exceptions.
That list of exceptions does not say anything about sharing grand-jury information with Congress for oversight purposes. But in making the ruling, the appeals court judges addressed the fact that their predecessors had permitted the Nixon-era Judiciary Committee to see such material.
The court decided that the Watergate-era step had been lawful because it could be interpreted as falling under an exception authorizing disclosure of grand jury material “in connection with a judicial proceeding.” The idea was that impeachment, which culminates with a trial in the Senate, is effectively a judicial proceeding.
For that reason, whether Judge Howell agrees that the Judiciary Committee is effectively conducting an impeachment-related investigation could make a legal difference. House Democrats are hoping she will conclude that their request falls into the Nixon-era precedent, when a formal impeachment inquiry was already underway.
There is no formal rule that says the full House must formally authorize an impeachment inquiry for the committee to conduct one. While the committee obtained such authorizations in both the Nixon and Clinton cases, it has carried out impeachment proceedings against federal judges without taking that step.