The ruling, which the Trump administration immediately moved to appeal, was a rebuke of Mr. Trump’s expansive view of executive power.

A federal judge says Gwynne Wilcox must remain at the agency that oversees relations among workers, labor unions and employers, setting up a Supreme Court showdown over presidential powers.

President Donald Trump’s firing of the former chairwoman of the National Labor Relations Board was an “illegal act,” a federal judge ruled Thursday, overturning her ousting in a decision that was highly critical of Trump’s “intent on pushing the bounds of his office.