Moreover, it’s hard to take the proposal seriously as outreach to the black community. National polling on stop-and-frisk is tough to come by, but both anecdotal and statistical data from New York suggest that black citizens view the practice as discriminatory and dehumanizing. In a 2012 Quinnipiac poll, seven in 10 black New Yorkers opposed stop-and-frisk. In 2013, Marist found an even higher proportion, 75 percent, wanted an overhaul.

Trump’s supposed black outreach has taken place to a great degree in white communities, before white audiences, while his appearances in African American communities have not always gone so well. His advocacy for stop-and-frisk offers more evidence for the view that Trump’s goal is not so much to court black voters but to convince white ones who are rattled about crime to back him.

This is one of the many contradictions of Trump’s recent moves. Even as he campaigns on the basis of “law and order,” he appeared at events in Ohio Wednesday with Don King, the boxing promoter who shot and killed a man (the death was excused as justifiable homicide) and served time for manslaughter after stomping a man to death in 1966. King’s speech in Cleveland was a strange, sporadically coherent stream of consciousness, in which he said, “I want you to understand, every white women should cast their vote for Donald Trump, not for Donald Trump the man but to knock out the system.”

One important question is what the Republican presidential nominee means by “stop-and-frisk.” As Donald Braman wrote in The Atlantic in 2014, “No one thinks a police officer with a reasonable suspicion that a suspect has a gun should be barred from frisking the suspect, but that is not what stop-and-frisk has come to mean,” i.e., stopping vast numbers of people for vaguely “suspicious behavior,” then searching them. Since Trump cited New York City, it seems reasonable to assume that’s what he meant.

Stop-and-frisk is not inherently unconstitutional, but the recent record shows that it’s hard to execute without racial discrimination. In New York, a federal judge deemed the city’s approach unconstitutional. Of city officials, Judge Shira Scheindlin wrote, “In their zeal to defend a policy that they believe to be effective, they have willfully ignored overwhelming proof that the policy of targeting ‘the right people’ is racially discriminatory and therefore violates the United States Constitution.”

Something similar happened in Chicago, where the American Civil Liberties Union of Illinois documented a pattern of racially disparate enforcement. The report came in March 2015. Among its findings: Blacks made up three-quarters of stops but less than a third of the city's population. Chicago’s police department decided to reach an agreement with the ACLU to install closer oversight.