“No one should be in jail for possessing marijuana,” said President Biden on Oct. 6, as he announced a “full, complete, and unconditional” pardon for any American convicted of marijuana possession, a federal crime under the Controlled Substances Act. The president’s pardon will not actually set anyone free, since the number of people serving time in a federal facility for possessing pot is — zero. In recent decades, roughly 6,500 defendants were convicted of simple possession, but all of them have served their sentences or been released. The new pardon will expunge the conviction from their records, which may make it easier for some of them to get hired or be approved for a loan. But anyone now incarcerated on drug charges would have been convicted of a more serious crime, to which this pardon won’t apply.

What if it did, though?

According to the Pew Research Center, more than 90 percent of Americans say marijuana use should be legal in at least some cases, with 59 percent saying it should be legal in all cases. So it’s a safe bet that Biden’s pardon of anyone who was prosecuted for marijuana possession won’t prove controversial. I certainly don’t want anyone locked up for mere possession of weed.

But I also don’t want presidents using the pardon power to invalidate laws they don’t like. Under the Constitution, “all legislative power” — that is, the power to make and repeal laws — belongs to Congress, not the chief executive. Yet doesn’t Biden’s blanket pardon effectively nullify the federal law against possessing marijuana? The law is still on the books — Congress hasn’t amended it, repealed it, or set a timetable for its expiration. But with his wholesale pardons to those convicted of violating the law, Biden has rendered it a dead letter.

Suppose it wasn’t just pot but all recreational drugs that Biden, or a succeeding president, wanted to decriminalize. There is, after all, a respectable body of opinion that scorns the War on Drugs as a colossal failure. If Congress cannot be persuaded to repeal the Controlled Substances Act, does the Constitution authorize a president to achieve the same end unilaterally, through a sweeping pardon of anyone convicted under federal laws banning the use or sale of cocaine, heroin, fentanyl, or LSD?

Imagine that a president who ardently supports the Second Amendment invokes his pardon power to release anyone sent to prison for possession of a prohibited firearm. Or a president who favors open immigration extending a “full, complete, and unconditional” pardon to anyone charged with unlawfully entering the United States.

Under the Constitution, a core responsibility of the president is to “take Care that the Laws be faithfully executed.” That language applies even to laws the president doesn’t support, as Dan McLaughlin noted in National Review. A president “can veto bad laws that are presented to him by Congress, and he can recommend that bad laws be repealed or reformed,” McLaughlin wrote, “but so long as the laws made by Congress are on the books, it is his sworn, solemn, constitutional duty to take care that they be faithfully executed.”

There is no way to square the president’s obligation to uphold the law with a reading of the pardon power so broad that, for all intents and purposes, it annuls a law he is supposed to enforce.

Presidents have for years abused their authority to issue pardons, but that abuse has typically taken the form of granting clemency to scumbags. Donald Trump’s 2017 pardon of Joe Arpaio, a brutal, dishonest, and racist Arizona sheriff, was a good example. So was Bill Clinton’s 2001 pardon of Marc Rich, a fugitive billionaire who fled to Switzerland after being indicted on 51 counts of fraud and tax evasion — and who just happened to be a major donor to Clinton’s presidential library foundation and Hillary Clinton’s Senate campaign.

Sleazy though such instances are, I have always thought they were a price worth paying in order to gain the potential benefits of the pardon power, which are considerable. The Framers of the Constitution knew that unscrupulous presidents might exploit their power of clemency to benefit crooked friends. But they also knew that clemency might be indispensable to justice. As Alexander Hamilton wrote in Federalist No. 74, without such an escape hatch, “justice would wear a countenance too sanguinary and cruel.”

Hamilton also anticipated that there might be “critical moments when a well-timed offer of pardon … may restore the tranquility of the commonwealth.” At its best, the pardon power has been invoked for just that purpose. The very first presidential pardon spared the lives of the ringleaders behind the Whiskey Rebellion, an armed uprising in 1794. Abraham Lincoln granted pardons to numerous Confederate soldiers and officials, in hopes of binding the wounds of a war-scarred nation. Gerald Ford pardoned his predecessor, Richard Nixon, in an effort to end the “long, national nightmare” of Watergate.

With similar motives of healing a painful breach, Jimmy Carter pardoned some 200,000 Vietnam draft evaders in 1977. By that point, the US withdrawal from Vietnam was four years in the past and the draft had been abolished. Carter’s grant of clemency, like the others just mentioned, was not designed to overturn a valid law but to reduce the heat of civil strife.

What Biden has done is different. His unconditional pardon of anyone convicted of possessing marijuana, an uncommonly silly law but one that has not been repealed, amounts to a usurpation of Congress’s powers. If presidents start using their pardon power to do away with laws they don’t like, we are headed for a grave constitutional crisis.

In an essay last summer, the Harvard Law Review warned that, unfettered, presidents could even use a plenary pardon to replace a duly enacted law with one of their own choosing. “Imagine Congress unanimously passed, over the president’s veto, a bill requiring jail time for police officers who killed unarmed civilians with chokeholds,” the review suggested. “A president who preferred only limited civil liability could unilaterally impose a different penal scheme by pardoning all such officers upon the condition they pay the victim’s family a sum of money not to exceed $500.” Even more outrageous examples can easily be imagined. And if there is one thing recent American history makes clear, it is the folly of trusting presidents to be restrained by a sense of outrageousness.

There are plenty of laws that Congress ought to get rid of, and presidents should feel free to urge their repeal. But while properly enacted laws remain in force, presidents are required to take care that they be faithfully executed. What Biden has just done is the opposite. The federal government shouldn’t be in the business of convicting Americans for possession of pot. But for presidents to manipulate the pardon power to undo an act of Congress is a far graver offense, and one that won’t end with marijuana.