The president is absolutely right. This movement focuses on the irrefutable fact that black citizens are far more likely than whites to die at the hands of the police. The more the country ignores that truth, the greater the civic discord that will flow from it.

The recent remarks of James Comey, the director of the Federal Bureau of Investigation, were not as racially poisonous as Mr. Christie’s, but they were no less incendiary. In a speech at the University of Chicago Law School on Friday, Mr. Comey said that heightened scrutiny of police behavior — and fear of appearing in “viral videos” — was leading officers to avoid confrontations with suspects. This, he said, may have contributed to an increase in crime.

There is no data suggesting such an effect, and certainly Mr. Comey has none. But his suggestion plays into the right-wing view that holding the police to constitutional standards endangers the public. Justice Department officials who have made a top priority of prosecuting police departments for civil rights violations — and who dispute that heightened scrutiny of the police drives up crime — were understandably angry at Mr. Comey’s speculations.

His formulation implies that for the police to do their jobs, they need to have free rein to be abusive. It also implies that the public would be safer if Americans with cellphones never started circulating videos of officers battering suspects in the first place.

A day after Mr. Comey made his remarks, The Times published a lengthy investigation into racial profiling and abusive police behavior in Greensboro, N.C., the third-largest city in the state. After reviewing tens of thousands of traffic stops and years of arrest data, Times reporters found that the police pulled over African-American drivers at a rate far out of proportion to their share of the local driving population. The police searched black motorists or their cars twice as often as whites — even though whites where significantly more likely to be caught with drugs and weapons.