President Joe Biden on Monday 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 the powers of the presidency in his final hours to guard against potential “revenge” by the incoming Trump administration.

The decision by Biden comes after Donald Trump 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 storming of the U.S. Capitol on Jan. 6, 2021. 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 pardons, announced with just hours left in Biden’s presidency, have 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 told NBC the pardons were disgraceful.

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.

It’s unclear whether those pardoned by Biden would need to apply for the clemency or accept the president’s offer. Acceptance could be seen as a tacit admission of guilt or wrongdoing, validating years of attacks by Trump and his supporters, even though those who have been pardoned have not been formally accused of any crimes.

“These are exceptional circumstances, and I cannot in good conscience do nothing,” Biden said, adding that “Even when individuals have done nothing wrong — and in fact have done the right thing — and will ultimately be exonerated, the mere fact of being investigated or prosecuted can irreparably damage reputations and finances.”

Fauci was director of the National Institute of Allergy and Infectious Diseases at the National Institutes of Health for nearly 40 years, including during Trump’s term in office, and later served as Biden’s chief medical adviser until his retirement in 2022. He helped coordinate the nation’s response to the COVID-19 pandemic and raised Trump’s ire when he resisted Trump’s untested public health notions. Fauci has since become a target of intense hatred and vitriol from people on the right, who blame him for mask mandates and other policies they believe infringed on their rights, even as hundreds of thousands of people were dying.

“Despite the accomplishments that my colleagues and I achieved over my long career of public service, I have been the subject of politically-motivated threats of investigation and prosecution,” Fauci said in a statement. “There is absolutely no basis for these threats. Let me be perfectly clear: I have committed no crime.”

Milley, a former chairman of the Joint Chiefs of Staff, has called Trump a fascist and has detailed Trump’s conduct around the deadly Jan. 6 insurrection. He said he was grateful to Biden for a pardon.