Where Does Biden Get the Authority To Mandate Vaccination?

President Joe Biden decreed on Thursday that private companies with more than 100 workers would have to make it a condition of employment for them to get vaccinated—either that, or take weekly tests for the virus. You may wonder: On what authority can Biden order this?

The White House is relying on the regulatory authority of the Labor Department's Occupational Safety and Health Administration (OSHA), an agency dating back to 1971, and in particular its seldom-used emergency powers. Some backers of Biden's action seem to think waving in OSHA's general direction,...