As a U.S. District Judge in Seattle, Judge James L. Robart typically handles federal cases affecting businesses and individuals in the western half of Washington state, an area roughly bordered by the Pacific Ocean in the west and the Cascade Range in the east.

But on Friday, Judge Robart expanded his reach, ordering a halt to President Donald Trump’s recent executive order on immigration and refugees. A federal appeals court early Sunday rejected a request from the Justice Department to immediately reinstate the order, asking...