WASHINGTON—A federal judge blocked most of a White House executive order punishing Perkins Coie, saying the administration had put itself at odds with the First Amendment by targeting the law firm based on President Trump’s dislike of its work for his political opponents.

U.S. law firm Perkins Coie has hired outside lawyers from Williams & Connolly in response to President Donald Trump's executive order last week punishing the firm over its prior work for Hillary Clinton and its internal policies promoting diversity and inclusion.

A law firm targeted by President Donald Trump over its legal services during the 2016 presidential campaign has sued the federal government over an executive order that seeks to strip its attorneys of security clearances.