Philip Allen Lacovara, a former president of the D.C. Bar, served as counsel to the Watergate special prosecutor.

After the final tumultuous months of the Nixon presidency, Gerald R. Ford decided to end the “long national nightmare” that was Watergate by pardoning his predecessor, thus sparing Richard M. Nixon from the dock where his senior aides awaited trial. Because I considered Ford’s pardon a serious mistake, I resigned in protest as the counsel to the Watergate special prosecutor. I hope that when President-elect Joe Biden assumes office, he will not repeat the same mistake.

Biden’s natural instinct is to let bygones be bygones. He demonstrated this when he brushed off attacks from Sen. Kamala D. Harris (D-Calif.) during the primary debates and chose her to be his running mate. Biden and some of his advisers may believe that the best way to close the book on the Trump presidency, with all of its corruption, abuse and mendacity, is simply to forget the past four years. In virtually any other presidential succession, this course might be prudent and consistent with our history of peaceful transitions without recrimination, vindictiveness or rummaging around for criminality.

But one need not embark on a malicious hunt to identify serious criminal abuses by Trump and many of his closest aides. Their conduct has revealed a pattern of disregard for the normal standards of public order, including those embedded in federal criminal statutes. The issue, therefore, is whether it is sound public policy to ignore these offenses to try to avoid further political rancor. There are three reasons why I think we cannot ignore them.

First, my reason for protesting Ford’s pardon of Nixon applies with even greater force now. The Watergate special prosecutor was appointed to demonstrate that “no person is above the law” — even a president. As White House tapes revealed, Nixon falsely assured some of his co-conspirators that, “when the president does it, it isn’t illegal.” Trump has publicly advanced an even more sweeping claim: In resisting grand jury subpoenas issued by New York state authorities for his tax records, Trump declared that a president enjoys “absolute immunity” from even being investigated for possible crimes. In July, the Supreme Court unanimously rejected that argument as inconsistent with constitutional doctrine — just as it did Nixon’s.

The problem I saw with Ford’s pardon of Nixon also applies to giving Trump a pass: Doing so would effectively treat a president, even if a former president, as above the law. Extending a pardon to Nixon while his co-conspirators — White House aides H.R. Haldeman, John Ehrlichman and attorney general John N. Mitchell — were on their way to prison created an unwarranted, privileged position for the former president. Although Biden is unlikely to issue a formal pardon to his predecessor, even deliberately ignoring Trump’s crimes would similarly signal that a president is not subject to equal justice under the law.

Second, although this is not the space to catalogue the numerous avenues of potential prosecution, it is sufficient to note that the report by then-special counsel Robert S. Mueller III lists perhaps 10 or more incidents of criminal obstruction of justice by Trump. More than 1,000 former Justice Department prosecutors publicly asserted that, but for Trump’s position at the time, any other person who had engaged in such conduct would have been indicted. It would be irresponsible to conclude that such serious offenses also should be ignored after Trump leaves office.

Third, the Constitution uniquely prescribes that a president must swear to “faithfully execute the Office of President of the United States.” This commitment dovetails with the primary duty of the president to “take Care that the Laws be faithfully executed.” The convergence between his duty and his oath imposes an obligation on the president to ensure that all laws of the United States, including its criminal laws, are enforced responsibly and equally against all persons. While prosecutors have some discretion about what charges to bring and even about whom to prosecute, it is no more permissible to conclude that former presidents should be excused from criminal culpability than it should be for former corrupt judges or pederast priests or bribe-taking television personalities.

I am not suggesting that Biden should order his attorney general to prosecute Trump and his close aides. I would detest any directive to “lock him up” as much as Trump’s “lock her up” chant. All that is necessary and appropriate is to make it unambiguously clear to career Justice Department prosecutors that they may apply normal prosecutorial standards in deciding what to investigate and whom to charge.

The collapse of the impeachment process makes it even more imperative to treat the criminal law as a real, available check on presidential abuses. Three presidents have been impeached, but none has been convicted. The requirement that two-thirds of the Senate vote to convict makes this constitutional remedy a virtual dead letter. If a person who succeeds in acquiring the presidency can flout the criminal law with impunity, then we will have rendered our republic unrecognizable to the Founders and dangerous for our descendants.