A handful of the key cases:eersandbeers wrote: I'd be interested in reading about some SCOTUS cases on this issue.
I don't see how federal regulatory agencies have any Constitutional authority whatsoever to make any type of law or regulation.
Cargo of the Brig Aurora v. United States, 11 U.S. 382 (1813)
Wayman v. Southard, 23 U.S. 1 (1825)
Field v. Clark, 143 U.S. 69 (1892)
J.W. Hampton, Jr., & Co. v. United States, 276 U.S. 394 (1928)
The major test is laid out in Panama Refining Co. v. Ryan, 293 U.S. 388. The modern doctrine is best found in Mistretta v. United States, 488 U.S. 361 (1989). You would probably be interested in Scalia's dissent in Mistretta.