A U.S. judge stopped Donald Trumps plan to cut money from sanctuary cities. These cities, like Los Angeles and Chicago, do not fully follow federal immigration rules. Judge William Orrick said the policy was not legal.

A federal judge on Friday extended a preliminary injunction that blocks President Trump from withholding funds from more than 30 “sanctuary cities” over policies that restrict local police from participating in immigration enforcement.

Judge William Orrick, a San Francisco-based federal judge appointed by Obama, blocked Trump from cutting sanctuary city funding. Here’s who he is and why his rulings matter.