Arizona's controversial immigration law was passed back in 2010 but Tuesday was the first time one of the more hotly contested provisions could be enforced.
U.S. District Judge Susan Bolton ruled that police can start enforcing the 'show me your papers' provision of the law after a two year legal battle. The ruling comes after a Supreme Court decision earlier this year that upheld the provision, reports CNN.
The provision doesn't mean police can check anyone's papers. But it does give them additional power to question immigration status in certain circumstances.