WASHINGTON — The Justice Department issued formal regulations Wednesday to restrict how federal prosecutors can pursue leak investigations, codifying a decision announced last year that officials would no longer take reporters’ phone records to try to identify the sources for stories that describe classified information.

“These regulations recognize the crucial role that a free and independent press plays in our democracy,” Attorney General Merrick Garland said in a written statement. “Because freedom of the press requires that members of the news media have the freedom to investigate and report the news, the new regulations are intended to provide enhanced protection to members of the news media from certain law enforcement tools and actions that might unreasonably impair newsgathering.”

First Amendment advocates welcomed the formal regulations issued Wednesday.

“This is a watershed moment,” said Bruce Brown, executive director of the Reporters Committee for Freedom of the Press. He called the change “a historic shift in protecting the rights of news organizations reporting on stories of critical public importance. For the last several years, we have worked with newsrooms to push for meaningful reform and are grateful to the Justice Department officials who saw this new rule over the finish line.”

The policy change followed revelations last year that the Justice Department, while investigating leaks of information, sought to obtain communications records of reporters at The Washington Post, CNN and The New York Times. Those investigations were meant to determine who had shared classified information with reporters during the Trump administration, but the investigations carried over into the Biden administration.

The Biden Justice Department faced criticism when it revealed the efforts this year, prompting President Joe Biden to declare he would no longer allow the practice of seizing reporters’ phone records, which he called “simply wrong.”

In the waning days of the Trump administration, the department secretly obtained the phone records of three Post journalists and tried unsuccessfully to obtain records of who they were emailing. Similar efforts were made regarding the communications records of a CNN reporter and four reporters at the Times.

In all three cases, the department had pursued the records as a means of trying to identify the sources of stories written in the first year of Donald Trump’s presidency; the reporters themselves were not targets of investigation.

Free press advocates and news media executives, including at The Post, have argued that issuing subpoenas for journalists’ records puts a chill on their ability to learn and report information about government activities. The Justice Department’s practice of issuing subpoenas to phone companies to review reporters’ phone records extends back to both Republican and Democratic administrations. President Barack Obama’s Justice Department had also faced criticism for its aggressive leak-hunting efforts, including collecting reporter records.

The new policy has some exceptions to cover activity not related to newsgathering. The prohibition on seizing reporters’ phone records would not apply to cases in which the reporter was suspected of committing a crime, acting on behalf of a foreign power or affiliated with a terrorist group – nor would it apply in cases where there is “an imminent or concrete risk of death or serious bodily harm, including terrorist acts, kidnappings, specified offenses against a minor . . . or incapacitation or destruction of critical infrastructure.”