President Trump on Friday reinforced how serious he is about reforming the regulatory state by nominating Neomi Rao to head the Office of Information and Regulatory Affairs. The OIRA administrator, or “regulatory czar,” is the ultimate policy wonk. Ms. Rao, a respected legal scholar with experience in all three branches of government, is ideally suited to the job.

OIRA, which operates within the president’s Office of Management and Budget, may be the most important office you’ve never heard of. Its staff of fewer than 50...