Just take a gander at @Bridget62945958, who published a series of anti-Semitic posts against my colleague Binyamin Appelbaum. One message showed a series of lampshades. Its caption read: “This is your family when Trump wins. Get your Israeli passport ready.”

Twitter suspended the account after Mr. Appelbaum brought it to the attention of Twitter’s co-founder and chief executive, Jack Dorsey, by way of his own Twitter feed. A new account sprang right up to continue the vitriol, prompting Jeffrey Goldberg, a national correspondent for The Atlantic, to write a post asking Mr. Dorsey, “How does it feel to watch Twitter turning into an anti-Semitic cesspool?”

Mr. Goldberg says he is torn about what Twitter should do, given that its cause — openness and free speech — is a reason he and so many other journalists are drawn to the service. “That’s the fundamental problem,” he told me. “At a certain point I’d rather take myself off the platform where the speech has become so offensive than advocate for the suppression of that speech.”

Twitter clearly wrestles with the same fundamental problem. It warns users they may not “threaten other people on the basis of race, ethnicity, national origin, sexual orientation, gender” and various other traits. Yet it often fumbles the enforcement. Charlie Warzel of BuzzFeed News unearthed a doozy last week.