President Trump’s fate went to the jury on instructions from Judge Juan Merchan that strike us as outrageous — and ripe for challenge. The judge’s instruction releases jurors from the obligation to make a unanimous decision on the key question. They “must conclude unanimously that” Mr. Trump engaged in an election conspiracy “by unlawful means,” the judge said. Yet, he added, “you need not be unanimous as to what those unlawful means were.”

At that point Judge Merchan supplied the jurors with a kind of à la carte menu for determining whether Mr. Trump had broken the law. “You may consider the following,” is how the judge introduced the three options. First, by “violations of the Federal Election Campaign Act otherwise known as FECA.” Second, by “the falsification of other business records.” Third, via “violation of tax laws.”

The instructions raise the prospect of Mr. Trump getting convicted but no one knowing of what. He could be “guilty” of using “unlawful means” without knowing what they were. That in turn suggests the jurors could have different conceptions of the case put forward by the prosecutors. Three jurors, say, might conclude that Mr. Trump broke tax laws, while nine decide he breached FECA. How would any New Yorker like to be in such a position?

This wouldn’t be so all-fired important except for the fact that the charge in question is the crime that prosecutors are relying on to transform into a felony the misdemeanors of which Mr. Trump is accused — falsifying business records. That’s because, as Judge Merchan told the jurors, to prove the felony crime, the law says “the intent to defraud must include an intent to commit another crime or to aid or conceal the commission thereof.”

So, the judge explained, prosecutors only need to “prove an intent to commit another crime or to aid or conceal the commission” of it. He added that “they need not prove that the other crime was in fact committed, aided, or concealed.” If Judge Merchan has stated the law accurately here, this appears about as fair as lowering the goalposts on one side of a football field, or enlarging the diameter of a basketball hoop.

This is not to say that Judge Merchan had told the jurors that they “don’t need a unanimous verdict,” as the Associated Press described some of the heated commentary that emerged earlier in the day. Each count in the prosecution’s indictment would, indeed, need to be agreed upon by all the jurors. Yet how can the wiggle room in the conspiracy charge not raise concerns about the coherence of the case brought by the Manhattan district attorney, Alvin Bragg?

These columns have noted doubts about Mr. Bragg’s politically motivated prosecution of a presidential candidate. As the case lurches to a close, the rickety nature of the case against Mr. Trump is coming into ever-clearer relief. It raises a further concern that if the jury convicts Mr. Trump under the rubric presented by Judge Merchan, it will present ample grounds for higher courts — perhaps even the Nine — to consider upon appeal.

This reminds us of the unrelated trial of one of the Sun’s founding directors, Conrad Black. The instructions given by the judge in his trial were that the jury had the authority to convict him of either pecuniary fraud or honest services fraud — and didn’t have to say which. So when the jury came in with a guilty verdict, Lord Black told the judge that he didn’t know of what he’d been convicted. Something similar is the result of Judge Merchan’s blunder.

In Lord Black’s case it went all the way to the Supreme Court, which, on a vote of nine to zero and an opinion written by Justice Ruth Bader Ginsburg, vacated his conviction and sent it back to a lower court, which greatly reduced his guilt. Bearing all that in mind, it seems to the Sun that if the jurors in Judge Merchan’s courtroom can’t agree on such a critical underlying fact in the case against Mr. Trump, the logic is for acquittal — now or on appeal.