An Atlanta district attorney is picking up the quest to charge President Trump after a Manhattan grand jury dissolved without indictments. The Fulton County district attorney, Fani Willis, a Democrat, likened the investigation to peeling an onion — raising the danger that any of us could find ourselves on the cutting board.

“You pull something back, and then you find something else,” she said, but she puts the sentence first and the trial afterward, like the Queen of Hearts, with the remark, “I’m going to write the elements to this crime are A, B, and C.”

That shows her mind is made up, that she’s already decided the former president guilty — and if she fails to find evidence to support her verdict, another prosecutor in another Democratic district will try his or her luck at the onion.

It was a chief judge of New York State, Sol Wachtler, who first said he could find a grand jury to “indict a ham sandwich.” So far, none of the Democratic DAs have managed to find citizens hungry enough for the Hero du Jambon au Trump.

Grand juries, like the Senate in four presidential impeachment trials across our history, have recognized that America cannot have one standard of evidence for people who are admired and another for those who are despised.

Because prosecuting former heads of state is the trademark of banana republics, historians consider President Ford’s pardon of President Nixon the right move, despite what many — but by no means all — Americans perceive as crimes.

When the worldwide left targeted President George W. Bush over the Iraq War, their crusade went nowhere, and they lost interest when he joined the chorus opposing Mr. Trump.

It helped that Mr. Bush is ineligible to run again. Since the 45th president may follow in the footsteps of the 22nd, Grover Cleveland, and regain power, some seek to win in court what their party might lose at the ballot box.

The legal process itself then becomes a punishment. The only American to serve as solicitor general, attorney general, and on the Supreme Court — Robert H. Jackson — warned against this sort of politicization of the prosecutorial power.

In 1940, he described the prosecutor’s power to destroy an individual with a “one-sided presentation of the facts” by launching an investigation as “most dangerous,” because he can “pick people that he thinks he should get, rather than pick cases that need to be prosecuted.”

Note that crime is skyrocketing in New York City in part because the Manhattan district attorney, Alvin L. Bragg, pledged to handle the pursuit of Mr. Trump “personally,” while ordering prosecutors to ignore the law on scores of crimes.

In his “Day One” memo, Mr. Bragg also stated, “The Office shall not seek a sentence of life without parole,” but had he been able to convict Mr. Trump, would he have been opposed to seeing him live out his days dressed like the Hamburglar?

Jackson warned in that same speech that it’s where “the prosecutor picks some person whom he dislikes or desires to embarrass — or selects some group of unpopular persons and then looks for an offense — that the greatest danger of abuse of prosecuting power lies.

“It is here that law enforcement becomes personal, and the real crime becomes that of being unpopular with the predominant or governing group, being attached to the wrong political views, or being personally obnoxious to — or in the way of — the prosecutor himself.”

In “Three Felonies a Day,” Harvey A. Silverglate details how federal prosecutors can target anyone, like the defendant in Kafka’s “The Trial,” who is arrested by forces of the state who never bother to detail charges or a crime.

Another warning against government seeking to punish a former commander-in-chief comes from President Tyler. A lifelong Democrat, he replaced the Whig Party’s William Henry Harrison and was the first targeted for impeachment.

A mob protested at the White House, congressmen threw punches, and a Whig representing Virginia in the House, John Botts, warned that if they didn’t impeach “His Accidency,” then “10,000 bayonets will gleam on Pennsylvania Avenue.”

When Tyler’s term expired in 1845, those grudges endured. His Whig neighbors appointed him overseer of his street — predecessor to the Department of Public Works — as a humiliation.

They soon regretted it. The office allowed Tyler to compel his foes to do roadwork whenever he saw fit, a power he exercised on holidays, at harvest time, and weekends.

Tyler was elected to the Confederate Congress in 1861. He died before ever taking his seat. Had he survived, however, there’s no reason to believe he would have been put on trial for treason. No member of the rebellion ever was.

America may yet indict and convict a former president, but after 250 years, our democracy’s cry remains not, “I’ll see you in court,” but, “See you on Election Day.” That’s because we are a nation of laws, not of ham sandwiches.