Legal Question in Constitutional Law in Texas

Re: constitution

It is not really "complete power to regulate the economy," as you state, but what you are referring to is called the "commerce clause" and has to do with interstate commerce, which is broadly defined, and commerce with foreign countries, as to all of which Congress is empowered:

"To regulate Commerce with foreign Nations, and among the several States, and with the Indian Tribes". Article I, Section 8, Clause 3 of the United States Constitution.

The Commerce Clause has been a judicial and political issue since the country's founding in 1789 concerning the extent to which Federal legislation may govern economic activity connected to interstate commerce but occurring within a state.

Its interpretation was greatly strenghtened by a series of cases in the early nineteenth century when John Marshall was chief justice, principally Gibbons v. Ogden in 1824.

It is now very broadly applied to anything which "affects" commerce so actiivities which appear purely to be in-state are often covered, for example, if they use the U.S. mail, telephone out of state, etc. so pretty much anything is subject to federal regulation.

New Deal legistation under FDR and civil rights legislation expanded its boundaries as well. Recent cases constrict its effect a bit, but in practical effect all commerce is federally regulated in one way or another.