Special counsel Robert S. Mueller III. (Charles Dharapak/AP)

James Comey is a former director of the FBI and a former deputy attorney general.

Attorney General William P. Barr will decide how much of special counsel Robert S. Mueller III’s findings and conclusions to share with Congress and the American people. Barr told the Senate Judiciary Committee he would try to be as transparent as possible while abiding by the Justice Department’s long-standing tradition of protecting the privacy rights of the innocent. That makes sense, but past departmental practices suggest he can release far more details than many people may now realize.

Providing detailed information about a completed investigation of intense public interest has long been a part of Justice Department practice. It doesn’t happen often, because ordinarily nothing outweighs the privacy interests of the subject of an investigation that ends without public charges. But department tradition recognizes that transparency is especially important where polarized politics and baseless attacks challenge law enforcement’s credibility. In critical matters of national importance, a straightforward report of what facts have been learned and how judgment has been exercised may be the only way to advance the public interest.

The Justice Department shared detailed information with the public after the FBI’s investigation of the 2014 killing of Michael Brown in Ferguson, Mo. His death at the hands of a white police officer touched off unrest around the country. The Justice Department responded to calls for a federal investigation, sending dozens of FBI special agents into Ferguson. After months of careful work, the department declined to bring a federal criminal prosecution. But the Justice Department didn’t just put the boxes in storage. Because there was intense, legitimate public interest — and significant doubt about law enforcement independence — the department publicly released an 86-page report in March 2015 detailing the entire investigation — what was done, what was found and how the evidence compared to governing legal standards, including an evaluation of the conduct and statements of individuals.

In October 2015, the Justice Department again shared information about a case involving corrosive doubts. For years, Republicans claimed that the Internal Revenue Service had illegally targeted tea party groups because of their political beliefs. In response to the allegations, the department did an extensive investigation, which ended with no charges being brought. But it didn’t stop there. Because the case posed a significant challenge to public confidence in the institution, the Justice Department provided Congress with an eight-page, single-spaced public report that laid out the investigation, the evidence found and a legal assessment. The department not only explained why no charges were appropriate but also discussed, by name, the conduct of a key subject of the criminal investigation — IRS supervisor Lois Lerner — writing that she had used “poor judgment” but that “ineffective management is not a crime. . . . What occurred is disquieting and may necessitate corrective action — but does not warrant criminal prosecution.”

These cases represent the way the Justice Department has always approached its mission — speak only in prosecuted cases, unless the public really needs to know. In 2004, during the George W. Bush administration, the public needed to know more about José Padilla, an American citizen captured in the United States and held by presidential order as an enemy combatant in a Navy brig. It was a breathtaking exercise of presidential power, one that generated intense and legitimate concern across the political spectrum.

The department had concluded a prosecution was not legally possible, but still told the American people what it knew about Padilla. To do that, the Justice Department provided Congress with a written report and laid out in a news conference detailed information about Padilla’s terrorist connections, his murderous plans and his confession. It was an extraordinary amount of information in an uncharged case. I know a lot about that announcement because I made it, in my role as deputy attorney general, after first being assured by the department’s career lawyers that speaking was consistent with law, policy and department tradition.

Like those examples, and many others, the Hillary Clinton case was one where the public interest required that we speak. Angry voices in July 2016 said we should have said nothing. But we were ending a criminal investigation of a candidate for president, one overseen by Justice Department political appointees from the candidate’s political party. The decision to decline prosecution would have been far less credible without those details, causing lasting damage to the department’s reservoir of trust with the American people. Democrats were wrong about transparency then.

But Republicans are wrong now, when they claim Justice Department rules forbid transparency about the completed work of the special counsel. It is difficult to imagine a case of greater public interest than one focused on the efforts of a foreign adversary to damage our democracy, and in which the president of the United States is a subject. I don’t know all the considerations that will go into deciding precisely what to say about the completion of the special counsel’s work and when to say it. It’s always important to consider guidelines and routines. But don’t listen to those who tell you transparency is impossible. Every American should want a Justice Department guided first and always by the public interest. Sometimes transparency is not a hard call.