https://s3.documentcloud.org/documents/21178567/scotus-mandate-rulings.pdf
Page 34, JUSTICE GORSUCH:
There is no question that state and local authorities possess considerable power to regulate public health. They enjoy the “general power of governing,” including all sovereign powers envisioned by the Constitution and not specifically vested in the federal government.
The federal government’s powers, however, are not general but limited and divided. Not only must the federal government properly invoke a constitutionally enumerated source of authority to regulate in this area or any other. It must also act consistently with the Constitution’s separation of powers. And when it comes to that obligation, this Court has established at least one firm rule: “We expect Congress to speak clearly” if it wishes to assign to an executive agency decisions “of vast economic and political significance.”
OSHA’s mandate fails that doctrine’s test.