This was illustrated to perfection recently in the case of Stéphan Turk in Nice. Just over a week ago, the jeweler, of Lebanese extraction, shot dead one of the two armed robbers who had threatened him with what looked like an automatic weapon. Mr. Turk pulled the trigger as they were making their escape, having relieved him of money and jewels. Mr. Turk was subsequently arrested and charged with voluntary homicide.

A page was set up on Facebook in support of the jeweler, and within a week it had accumulated 1.6 million “likes.” There has been nothing remotely like this in France before: Evidently the case touched a very raw nerve. Some of the Facebook messages of support of Turk have been startling in their vehemence. “He should be given the Légion d’honneur,” writes one supporter. “One parasite less,” observes another. “No justice for them, just a bullet in the head. Sick of being bothered by little s—.” Also: “It’s deplorable that we should have to kill these scum ourselves.” “The only thing I reproach the jeweler with is that he didn’t get the other,” wrote another of Mr. Turk’s supporters…

The man whom Mr. Turk killed, Anthony Asli, would have been 20 in October. According to Le Monde he looked 16, and in the words of his understandably distressed father he was still “a little boy.” But this little boy already had 14 convictions (which means that he must have committed at least 50 crimes), among them robbery with violence. He had, not long before his death, come out of prison for the theft of a motor scooter. Between coming out of prison and being killed, he had time to make his girlfriend, two years older than he, pregnant. The armed robbery he committed against Mr. Turk did not bode well for his future: If ever there was a murderer in the making, it was he.