Illinois Gov. Bruce Rauner signed a bill Monday that sharply curtails the ability of law enforcement officials across the state to detain criminal immigrants on behalf of federal authorities.

After months of deliberating over what to do with the so-called Illinois TRUST Act, the first-term Republican signaled last week that he would approve the measure, which effectively ends the practice of honoring Immigration and Customs Enforcement (ICE) detention requests — commonly known as “detainers” — unless they are backed by a criminal warrant.

Rauner signed the bill at a crowded ceremony in Chicago’s Little Village neighborhood, the heart of the city’s Mexican-American community. Immigrant advocates celebrated the new law, calling it the “gold standard” for state protections against deportation, reports the Chicago Sun-Times.