In Philadelphia, the police commissioner pulled 72 officers from the streets and said some would be fired. In Phoenix, the chief gave some officers “nonenforcement” duty. In St. Louis, the top prosecutor said she would no longer accept cases from 22 officers.

The reason: A catalog of bigoted social media posts by members of law enforcement that has led to upheaval at departments across the country and undermined longstanding efforts to improve interactions between police officers and the people they serve.

“They will undeniably impact police-community relations,” said Richard Ross Jr., the Philadelphia commissioner, when he announced the benching of his officers on Wednesday. “We are not naïve to that fact, nor are we dismissive of it.”

The public posts, compiled from accounts believed to belong to current or former officers in eight departments, included racist, misogynist and Islamophobic memes and comments, as well as celebrations of officers who use excessive force, including messages like “It’s a good day for a chokehold.” The compilation was released this month by the Plain View Project, a database of officers’ social media activity.

The posts drew new attention to long-simmering concerns about prejudice and aggressiveness in American police departments, but they also raised questions about free speech, and about how much latitude chiefs have to penalize legal, if offensive, views shared by their employees while off duty.

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In Philadelphia, Commissioner Ross said 72 officers had been assigned administrative duties while facing investigation for their social media posts, the largest single removal of officers from street duty that he could recall in his roughly 30-year career. He said some of the officers were likely to be fired, and many could be disciplined.

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He described the posts as disturbing, and said they tarnished his department’s reputation. But he said that some of the posts were protected by the First Amendment. The city has hired a law firm to help determine which posts were acceptable speech and which were not, he said. Court rulings have permitted limited restrictions on the speech of public employees if it is potentially harmful.

The job description includes obeying the law and applying it fairly.

If their posts show that they are unwilling to do so, fire them.