Every once in a while, when you ride the subway in New York City, you're treated to a free, spontaneous performance. Most times, it goes like this: A teenager yells "Showtime!", some boring dolts groan and stare at the floor, and an impossibly limber body starts flying.

A good subway dance is every bit as thrilling as ballet, or well-played basketball, or a string quartet playing Bartók. It is also illegal, and good-guy mayor Bill de Blasio and his police commissioner Bill Bratton are cracking down. In July of 2013, the NYPD had arrested 40 people on the year for breakdancing, cartwheeling, and swinging from handrails; this year, that number jumped to 240.

Bratton justified the arrests by invoking the "level of fear" that dancers inspire in New Yorkers. From the Associated Press:

"Is it a significant crime? Certainly not," Bratton said recently. But the question is, he added, "Does it have the potential both for creating a level of fear as well as a level of risk that you want to deal with?"

What does the average subway dancer look like? He is a teenager, he wears loose-fitting athletic clothes, and he is black.

Commissioner Bratton says low-level "broken windows" arrests like these — taking down the likes of dancers and panhandlers — are necessary to maintain order, because they scare people away from committing more serious crimes. Setting aside whether that's even true, we're left with a troubling reality: In a city that still knows racial segregation intimately, with a police force that regularly assumes young black men are criminals, sending a few dozen more kids of color into the criminal justice system for having a little fun is worth it if it means protecting the sanctity of a showtime-free subway ride.

[Image via AP]