Elliot Williams was a deputy assistant attorney general at the Justice Department from 2013 to 2017.

President Trump’s pardon of former national security adviser Michael Flynn didn’t merely save one man from going to federal prison. Far more importantly, the pardon demonstrated the wisdom of U.S. District Judge Emmet G. Sullivan’s refusal to dismiss the case against Flynn. In the end, the judge’s steadfastness saved the Justice Department from itself — or at least from its attorney general.

Flynn was one of six associates of the president who were investigated and charged with federal crimes as part of special counsel Robert S. Mueller III’s inquiry into Russian interference in the 2016 campaign. In open court, Flynn entered a knowing, voluntary and intelligent guilty plea to a felony charge for lying about his substantive contacts with the Russian ambassador to the United States. However, last May, acting on instructions from Attorney General William P. Barr, the Justice Department did a startling about-face in the case, seeking to dismiss it by arguing in court that prosecutors should never have brought the case in the first place.

Enter Sullivan — a judge before whom I have appeared, and who I can attest is not one to suffer fools. He declined to dismiss the case, instead bringing in an outside adviser who argued that the Justice Department’s argument smelled curiously like pretext for seeking to dismiss the case to benefit a political ally of the president.

Sullivan’s healthy skepticism of the Justice Department’s arguments ensured that the branches of our government functioned as they were supposed to, and that no one branch was allowed to hide from the costs of its actions. The president and his allies have repeatedly attacked the special counsel’s investigation from its earliest days, characterizing it as a partisan witch hunt fixated on Trump’s undoing. Once Flynn was charged, it was only a matter of when, not if, the president would pardon him.

Under the law, nothing could have stopped the president. Article II, Section 2 of the Constitution grants the president an exceptionally broad pardon power over federal offenses, with virtually no caveats. As the Supreme Court said in 1866, the power was largely “unlimited. . . . It extends to every offence known to the law, and may be exercised at any time after its commission.”

Which made the Justice Department’s decision to drop the charges so perplexing. At any point — even prior to Flynn’s having been charged in the first place, as pardons can be prospective — Trump could have issued a full pardon. The decision to withdraw charges can only be explained, then, as an attempt by the president and attorney general to produce the effect of a pardon (that is, vacating a criminal conviction), without incurring any of the natural political costs of granting a pardon.

Presidential acts of clemency can carry political costs: George W. Bush’s commutation of I. Lewis “Scooter” Libby’s prison term, Bill Clinton’s pardon of Marc Rich, and George H.W. Bush’s pardon of Caspar Weinberger still linger over the three presidents’ legacies. Such is the cost of exercising unreviewable power. However, passing the Flynn pardon off onto the Justice Department would have been an attempt to deputize prosecutors in carrying out a political favor for the president. It would have hidden political cronyism in the dry, apolitical packaging of legalese.

Sullivan had to have known this. By rejecting the Justice Department’s attempts to get out of the case, he was not digging in to stick it to a defendant he might have thought was guilty. He was protecting the justice system as an institution, ensuring that it wasn’t perverted by the Trump administration and the attorney general.

Sullivan, in effect, forced the president to personally carry out his constitutional duty and not pass off his dirty work to the courts and justice system. That the decision might have been politically costly is borne out by the timing of the pardon; it cannot be an accident that the pardon came only days after the president’s tacit public acknowledgement that he lost his reelection bid.

In short, the episode introduced the country to a federal judge acting as a steward of the separation of powers, ensuring that one of the political branches of government carried out its duties properly. He made the president do his job, and stopped the attorney general from trampling on career employees who were doing theirs.

As John Adams wrote to Thomas Jefferson on Feb. 2, 1816, “I say, that Power must never be trusted Without a Check.” Today, we can be grateful for at least one federal court providing that check and keeping our political leaders honest.

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Leticia and her son crossed the Rio Grande seeking asylum from danger in Guatemala. Instead, they were torn apart by a policy designed to inflict trauma. (Jeremy Raff, Connie Chavez/The Washington Post)

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