U.S. District Judge Amy Berman Jackson ruled on Saturday that Office of Special Counsel head Hampton Dellinger can remain in his role after President Donald Trump tried to terminate him without clear cause.

A federal judge said that the president’s efforts to remove Hampton Dellinger, who leads the Office of Special Counsel, were unlawful. The agency protects whistle-blowers.

The federal judge’s decision blocks Trump from removing Hampton Dellinger as head of the Office of Special Counsel and sets up a likely Supreme Court battle over the president’s powers.