Cook County State’s Attorney Anita Alvarez ended up empty-handed last week — and all of Chicago can celebrate. Alvarez lost a U.S. Supreme Court mission that would likely surprise most citizens of this progressive city Chicagoans: to strip them of their First Amendment rights and to allow her to prosecute citizens for videotaping police in public.

Alvarez’s position was denounced as extremist by a federal appellate court and civil libertarians around the country. However, she refused to yield to the courts, to the Constitution or to the public — making Chicago a leader of a national effort to bar the use of a technology widely considered the single most important deterrent of police abuse. Alvarez is not alone in this ignoble mission, and this threat to the public is not likely to pass with her latest defeat.

It was 21 years ago that a citizen filmed the savage beating of Rodney King by Los Angeles police officers after a high-speed car chase. The most chilling fact in the King case was that, absent the videotape, this would have likely been dismissed as another unsupported claim of police abuse.

Since that time, numerous acts of abuse by police have been captured by citizens — exposing false charges and excessive force often in direct contradiction to sworn statements of officers. These cases have increased exponentially with the explosion of cellphones with videotaping capabilities. Chicago has seen a long litany of such cases.