Mayor Adams is making a mistake, in our view, in arguing against the right of New Yorkers to stand their ground in self-defense when they fear for their lives in New York. The error has never been more glaring than in the case of Jose Alba, who defended himself from a man who had cornered him behind the counter of his bodega and who, Mr. Alba feared, was going to kill him.

The case has outraged New Yorkers on the right and left — and for good reason. For defending himself, Mr. Alba was hauled off to Rikers Island and held, at first, on $250,000 in bail and faced something like 20 years. For, again, defending himself, meaning for exercising one of the oldest rights — even the oldest right — in Anglo Saxon law, a tradition that has so enriched our own laws.

This has all been well-covered by our Raina Weinstein, whose latest dispatch, out today, notes that Hizzoner has expressed sympathy for Mr. Alba but he has refused to call for dismissing — or even reducing — the murder charges against Mr. Alba. Nor has he been willing to support Mr. Alba’s right of self defense or back recent calls in Albany for stand-your-ground legislation.

“My heart goes out for this hardworking, honest New Yorker that was doing his job in his place of business, where a person came in and went behind the counter and attacked him,” Ms. Weinstein quotes the mayor as having said last week. Yet, she reports, the mayor claims to “support hard-working, innocent people that are doing their job.” So which is it?

The least credible part of the position the mayor is taking has to do with the explanation his office offers for his opposition to a stand-your-ground law. “On stand your ground,” his office has said, “the NYPD has been entrusted to protect the people of New York City, and that is who the mayor believes should continue to defend New Yorkers every day.”

We share the mayor’s regard for the NYPD. We have little doubt that had officers been in the Bodega when Mr. Alba was attacked, the man who attacked him might still be alive. There were no officers in the bodega, though. All Mr. Alba was able to find was a knife, with which he defended himself. New York requires Mr. Alba to retreat, but the evidence suggests Mr. Alba was cornered.

We understand that Mr. Adams is in a difficult spot. As a state senator, Ms. Weinstein notes, he was adamantly opposed to “stand your ground” legislation when a bill was presented in the state Senate. In 2012, he led the fight against a stand-your-ground bill advanced by four GOP state senators that would have excised the duty to retreat.

“‘Stand your ground’ has been cited in many questionable situations where it is obviously unwarranted as self defense,” Mr. Adams wrote back then. We’re prepared to stipulate the mayor is right on that head. Even so, that’s not a reason to deny the right to stand one’s ground and, in doubtful situations, let a jury sort out the facts. Juries are in the business of drawing distinctions.

Mayor Adams cites the Trayvon Martin case. We fail to see the similarity. Florida has no duty to retreat. Even with a duty to retreat in New York law, it is hard to see how Mr. Alba could have retreated. Hence our view that the mayor should be coming to his defense. The mayor might be a former police officer but, as mayor, he has a far larger responsibility.