Big blue cities are embracing conservative anti-crime measures. Here’s why.

San Francisco’s liberal voters just endorsed drug screenings for welfare recipients. D.C.’s progressive City Council passed a crime package Tuesday that will keep more people in jail while awaiting trial. And New York’s governor on Wednesday ordered hundreds of National Guard troops to deploy inside the city’s troubled subway system.

The country’s biggest, bluest cities are embracing tough-on-crime policies that would have been politically heretical just a few years ago — ratcheting up criminal penalties and expanding police power amid fear and anger over a rash of brazen crimes like...