What makes the police encounters chilling is how routine they are.

They happen while black people are going about their everyday lives, only to be interrupted by someone calling the police for the thinnest of suspicions.

In the past month, more than a handful of such interactions have attracted widespread attention on social media — and, in turn, in national outlets like The Times, CNN and The Washington Post.

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“It happens so frequently to people of color that we don’t often think of it as a big deal or as particularly newsworthy,” said Paul Butler, a Georgetown University law professor who is the author of “Chokehold: Policing Black Men.”

He added, “It’s humiliating and aggravating and upsetting, but the idea that it’s national news is unexpected.”