WASHINGTON >> The Justice Department will soon receive a final accounting from Robert Mueller, the special counsel, of his nearly two-year investigation into how Russia influenced the 2016 election, whether the Trump campaign participated in those efforts and whether President Donald Trump obstructed justice.

But there is no guarantee the public will ever see that full report. The special counsel regulations say Mueller must submit a confidential report outlining his prosecutorial decisions to the attorney general, William P. Barr, and that the attorney general must then send a summary of that work to Congress.

The regulations leave Barr considerable flexibility as to how much detail he provides to Congress and the public, discretion that was built into the regulations in response to independent counsel Ken Starr’s decision to give Congress a lengthy — and, critics said, salacious — report on his investigation into President Bill Clinton’s sexual relationship with a young White House intern.

Once the special counsel’s office delivers its report and closes its doors, the work of the Justice Department and Congress to inform the public of Mueller’s findings begins. While Barr must tell lawmakers why the special counsel’s work concluded, he does not have a legal obligation to give them the full details of Mueller’s report.

Although there have been high-profile exceptions, the Justice Department generally does not publish derogatory information about individuals not charged with crimes. As a result, it is not clear how much information, if any, Barr would choose to include about Trump and other key figures in the investigation if there are no charges against them.

Congress, for its part, is unlikely to be satisfied with anything short of a full copy of Mueller’s work. Democrats have expressed concern that Barr harbors a pro-Trump bias, in part due to his expansive view of executive power and also because, before being nominated as attorney general, he wrote a 19-page memo arguing that Trump’s decision to fire James Comey as FBI director was not an act of obstruction.

Democratic lawmakers are now debating how best to get the information that they believe must be shared with Congress, and by extension the public.

“Barr should release the report with minimal redactions,” Sen. Dianne Feinstein, D-Calif., said in a statement this month. “The subjects of the investigations get to the very root of our democracy, and to withhold it from the American people would be absolutely unacceptable.”

Barr said during his confirmation hearings that he would be as transparent as possible within the scope of the special counsel rules.

What does Barr do once he has the report?

The Justice Department will comb Mueller’s report for classified information and for grand jury testimony that cannot be shared in whatever summary Barr provides to Congress.

“Barr has to make sure that the investigators’ sources and methods are not going to be compromised and that grand jury information is protected,” said Neal Katyal, a former department official who wrote the special counsel rules.

Justice Department lawyers will have to balance the value of disclosing information that bolsters the public’s faith in the department’s integrity with the risk of compromising national security or other sensitive information. Depending on the length of the report, the process could take days or more than a week.

How much detail must Barr give to Congress?

The special counsel regulations, created in 1999, say that Barr must provide a report to the senior Republicans and Democrats on the House and Senate Judiciary Committees. The report must explain why Mueller’s work concluded and list any times the attorney general told the special counsel’s office it could not take a proposed action.

The regulations are not specific about how much detail Barr must provide, stating that the attorney general could publicly release the report if he determines it is in the public interest.

Barr has said he will hew closely to the rules, which give him the option of sharing only a bare-bones accounting of the Mueller report. Democrats in Congress have said they want to see the whole thing.

“Regulations governing special counsel Mueller’s investigation do not prohibit Attorney General Barr from disclosing Mueller’s final report and investigative materials to Congress,” Feinstein said in a statement Friday, “and I repeat my call for the attorney general to provide the report unedited once it has been provided to him.”

How much detail will Barr provide about the president?

Some of the key questions in the special counsel’s investigation concern whether Trump was working on behalf of Russia and whether he obstructed justice, serious allegations that could result in criminal charges.

A long-standing Justice Department opinion says that a sitting president cannot be criminally indicted, guidance that makes it unlikely Mueller will charge Trump. Because of the department’s practice of not making derogatory statements about people who are not charged with crimes, Barr would have cover, if he chose to use it, to omit any damning information Mueller might transmit to him about Trump.

Comey caused a public outcry in summer 2016 when he said after an investigation that “no reasonable prosecutor” would charge Hillary Clinton, but then publicly excoriated her use of a private email server.

But Katyal said there was an important difference between Comey’s handling of the Clinton investigation and the choice that Barr faces: Unlike Clinton, he said, Trump controls the Justice Department, essentially leaving Congress to hold him accountable for misdeeds. Barr’s summary could act as the road map Congress needs to fulfill its oversight role and weigh the possibility of impeachment.

The question of how or whether the department would handle a referral to Congress for impeachment remains unclear.

If Mueller found that the president committed a grave offense and wants Congress and the world to know, he could seek an indictment of the president. If Barr then chose to stick with the department’s opinion that a sitting president cannot be indicted, he would have to inform Congress of that decision, because the special counsel rules require the attorney general to tell Congress of any time he denied a proposed action by the special counsel and why.

“The special counsel regulations grapple with how to police high-level executive branch wrongdoing,” Katyal said. “If a sitting president can’t be indicted, then Congress must decide whether it must act, and it would need more information from Mr. Barr to make that decision.”

What can Congress do once it receives the summary?

If lawmakers are not satisfied by the summary Barr provides, they can begin the process of extracting more information from the Justice Department by requesting documents and subpoenaing information, including the Mueller report itself.

Congress can also call witnesses, including Mueller, to testify in a public hearing or a private deposition. And lawmakers can use their bully pulpits to publicly pressure Barr for more information, tying the Justice Department up in hearings and subpoena fights that last for the rest of Trump’s time in office.

Democratic leaders are already laying the groundwork to obtain as much information about the Mueller report as possible, saying the department has established a precedent of giving Congress sensitive information.

“In other closed and pending high-profile cases alleging wrongdoing by public officials, both the department and the FBI have produced substantial amounts of investigative material, including classified and law enforcement sensitive information,” Rep. Jerrold Nadler, D-N.Y., chairman of the House Judiciary Committee, and other Democratic committee leaders said in a letter to Barr on Friday.

© 2019 The New York Times Company