Various authorities were assigned from these Independent States to the single federal government under the Constitution, such as making international treaties and resolving conflicts between the states including interstate commerce. The powers allowable under "interstate commerce" broadened in the 1930s.
But I've read that the first version of CLIA (CLIA 67) applied only to laboratories that were "interstate" laboratories, and to hospitals received CMS dollars. Later, CLIA was quietly expanded by legislation to apply to all human medical testing.
So what about the VALID ACT, which has been incorporated into the Senate version of current FDA legislation? It allows the FDA to regulate LDT diagnostic tests as "interstate commerce." Critically, section 587AA(b) says:
"Any in vitro clinical test that is offered, including by making available for clinical use in the United States, is DEEMED TO BE AN ACT that constitutes introduction into interstate commerce for the purpose of enforcing the requirements of this Act."
You probably see where I'm heading. If VALID passes, surely some local hospital will want to take this to the Supreme Court, with the argument that offering a local LDT test to its own patients on its own campus is not a reasonable interpretation of what the Founding Fathers would have viewed at the time as active "interstate commerce." (Look for someone to quote from a 1785 dictionary on the meaning of "interstate.") That is, you would argue to the Supreme Court that just because somebody pens a definition that a local in-house LDT is "interstate commerce," that doesn't mean the SCOTUS has to agree with the author of the bill.
In the 40,000 words of the VALID ACT, the term "interstate commerce" occurs 23 times.