WASHINGTON — Joe Biden, in one of his final acts as president, pardoned Dr. Anthony Fauci, retired Gen. Mark Milley and members of the House committee that investigated the Jan. 6 attack on the Capitol, in an extraordinary use of executive power to guard against potential “revenge” by the new Trump administration.

The decision Monday by Biden came after now-President Donald Trump had warned of an enemies list filled with those who have crossed him politically or sought to hold him accountable for his attempt to overturn his 2020 election loss and his role in the Capitol siege four years ago. Trump has selected Cabinet nominees who backed his election lies and who have pledged to punish those involved in efforts to investigate him.

“The issuance of these pardons should not be mistaken as an acknowledgment that any individual engaged in any wrongdoing, nor should acceptance be misconstrued as an admission of guilt for any offense,” Biden said in a statement. “Our nation owes these public servants a debt of gratitude for their tireless commitment to our country.”

The prospect of such pardons had been the subject of heated debate for months at the highest levels of the White House. It’s customary for a president to grant clemency at the end of his term, but those acts of mercy are usually offered to Americans who have been convicted of crimes.

Trump said after his inauguration that Biden had pardoned people who were “very very guilty of very bad crimes” — “political thugs,” Trump called them.

Biden, a Democrat, has used the power in the broadest and most untested way possible: to pardon those who have not even been investigated. His decision lays the groundwork for an even more expansive use of pardons by Trump, a Republican, and future presidents.

While the Supreme Court last year ruled that presidents enjoy broad immunity from prosecution for what could be considered official acts, the president’s aides and allies enjoy no such shield. There is concern that future presidents could use the promise of a blanket pardon to encourage allies to take actions they might otherwise resist for fear of running afoul of the law.

“I continue to believe that the grant of pardons to a committee that undertook such important work to uphold the law was unnecessary, and because of the precedent it establishes, unwise,” said Sen. Adam Schiff, D-Calif., who worked on the committee. “But I certainly understand why President Biden believed he needed to take this step.”