A U.S. district judge ruled Tuesday that police officers in Arizona can begin questioning the immigration status of people they stop while enforcing other laws. The Supreme Court upheld the controversial so-called “show-me-your-papers” law in June, holding that it didn’t interfere with federal statutes. Today’s decision allows police to begin enforcing the policy immediately. Opponents of the law—parts of which have been in effect since 2010—asked Judge Susan Bolton to block its implementation in July on the grounds that it would promote racial profiling. President Obama has criticized the law, but federal officials say they will help uphold the policy so far as it helps remove repeat violators who may threaten national security.