A good offense is the best defense, they say — which would suggest that if Mayor Adams believes his federal prosecution for treating with Turkey is political payback for his criticism of President Biden’s migrant policies, he ought to make that case to the public. “I always knew that if I stood my ground for New Yorkers that I would be a target,” Mr. Adams avers. So is the prosecution of Mayor Adams at bottom political? 

Mr. Adams’s political future could depend on the answer. To make the case, he would doubtless point out that he began his mayoralty touting himself as “the Biden of Brooklyn,” after campaigning on a pledge to preserve New York City’s status as a migrant-friendly sanctuary city. President Biden hosted Hizzoner at a White House anti-crime event in 2021 and in 2022 Mr. Biden appeared with the mayor at another event detailing anti-gun violence strategies.

Yet the relationship suddenly soured as the Biden-Harris open border led to a surge of migrants. Mr. Adams griped in April 2023 that the “president and the White House have failed this city.” In September 2023 he warned that the migrant flood “will destroy” the city. He earned no favors with “the Big Guy” by calling himself the “new face of the Democratic Party.” That, Politico reports, “only encouraged speculation about a future White House run.” 

The next thing Mr. Adams knows, he is en route to Washington for talks at the White House over the migrant crisis and meetings on Capitol Hill. But “minutes before the meeting,” the New York Post said, Mr. Adams cancels “his entire schedule at the nation’s capital” and races back to Gotham. It turns out the FBI chose the day of Mr. Adams’s trip to raid the homes of one of his top fundraisers and his international affairs aide. Was this timing coincidental?

It’s not our intention here to suggest that federal prosecutors — who, as Justice Department employees, report to the president — were motivated by political bias. The White House denies any coordination with prosecutors. A spokesman for New York’s Southern District declined to comment. For good measure, Politico wrote, an unnamed White House official said of Mr. Adams that “It’s been a long time since any of us gave him much real thought.”

A throwaway remark like that might not serve as evidence of malice at the White House. Nor does bad blood between president and mayor, per se, constitute proof of a political prosecution. Were Mr. Adams to mount such a defense, he would, one imagines, need to marshal more substantive proof of bias. More broadly, though, prosecuting an elected official is a fraught prospect of the kind that FDR’s Attorney General, Robert Jackson, warned against.

In his famous speech to United States attorneys, Jackson observed that “if the prosecutor is obliged to choose his cases, it follows that he can choose his defendants.” He called it “the most dangerous power of the prosecutor: that he will pick people that he thinks he should get, rather than pick cases that need to be prosecuted.” That means “picking the man and then searching the law books, or putting investigators to work, to pin some offense on him.” 

In that event, Jackson explained, “law enforcement becomes personal.” Mr. Adams’s lawyers, when trying to head off the charges that Mr. Biden’s Justice Department were devising, tried to warn against this, the New York Post reports. Hizzoner’s lawyers argued that the charges being contemplated were “on flimsy legal ground,” the Post reports, in light of the Supreme Court ruling in U.S. v. McDonnell, a case that narrowed the legal definition of corruption.

Indeed, McDonnell, a unanimous decision, could be decisive in Mr. Adams’s case. Chief Justice Roberts’s opinion chastised the Justice Department for criminalizing “the most commonplace requests for assistance” from elected officials. The chief also cautioned against involving the “Federal Government in setting standards” of “good government” for local officials. In the end, isn’t it the voters, and not Mr. Biden’s minions, who should decide Mr. Adams’s fate?