If prosecutor Alvin Bragg’s case is this much of a stretch, he should think twice.

Donald Trump’s estranged lawyer Michael Cohen testified for three hours before a New York grand jury, and Mr. Trump has also been invited to appear, a sign that the investigation by Manhattan District Attorney Alvin Bragg might be nearing its denouement. The public can hope Mr. Bragg is thinking hard about whether it serves justice to indict an ex-President and 2024 candidate under a baroque legal theory that might fail in a criminal trial.

News reports say Mr. Bragg is considering a charge of falsifying business records. The gist would be that Mr. Trump’s $130,000 hush money to Stormy Daniels in 2016 wasn’t accounted for properly. When Mr. Cohen was sentenced to prison in 2018, federal prosecutors said that after he paid off Ms. Daniels he was reimbursed “in monthly installments disguised as payments for legal services performed pursuant to a retainer, when in fact no such retainer existed.”

But falsifying business records is typically a misdemeanor in New York. To become a felony, prosecutors would have to prove the books were cooked with “an intent to commit another crime or to aid or conceal the commission thereof.” In Mr. Trump’s case, what is this second crime? The suggestion in the press is Mr. Bragg might say it’s a campaign-finance violation, that the cash to Ms. Daniels was an impermissible donation to Mr. Trump’s presidential bid.

Really? An elected Democratic prosecutor is going to indict a Republican former President and 2024 contender, alleging a felony that could put him in prison, and it would boil down to a campaign-finance violation?

That would be some precedent. To the public, it would sound as if Mr. Bragg is scrambling to come up with a legal theory to fit a target he had already decided he wanted to charge.

Mr. Trump might argue in court that the payoff to Ms. Daniels was mainly a personal expense, motivated by a desire to stop a blowup with his wife.

And did Mr. Trump have “intent” to breach campaign-finance law?

Even the New York Times, which threw fairness out the window during the Trump years, reports that, “The case against the former president hinges on an untested and therefore risky legal theory involving a complex interplay of laws, all amounting to a low-level felony.”

Perhaps Mr. Bragg has gathered more substantial evidence than the news leaks are letting on. But if Mr. Bragg tries to bootstrap a violation of campaign-finance law into a felony, half the country would conclude that the Manhattan DA is engaged in politics by other means. He’d be running the risk that at least one juror might refuse to play ball. Mr. Bragg could go down as the man who stretched the law to indict a former President, and then lost.

None of this is a substantive defense of allegedly paying off a former mistress and then disguising the transaction. Mr. Trump, for the record, denies that any fling with her took place. Whatever the case, the criminal code isn’t an all-purpose tool for righting moral wrongs, and in the political arena voters have the final say.

Mr. Cohen went to prison, but the U.S. Attorney’s office for the Southern District of New York said he also hid $4 million from the IRS and lied to bankers to get a $500,000 loan. The feds haven’t charged Mr. Trump for l’affaire Stormy Daniels, and perhaps there’s a good legal reason.

— The Wall Street Journal