It seems that the ULC would require federal legislation otherwise everything they've done is unconstitutional. (I haven't come across any such act of law as of yet.)

It also seems that the people within the individual states have little to no say in the activities of and proposals made by the ULC, who's members frequently also consist of state legislatures. Hence, proposals made by the ULC to individual states effect an echo chamber wherein the process of ratifying those proposals into law are for the most part a mere formality.


U.S. Constitution A.I,S.10:

No state shall enter into any treaty, alliance, or confederation; ...

No state shall, without the consent of Congress, ...enter into any agreement or compact with another state...

https://www.uniformlaws.org/aboutulc/overview

https://en.wikipedia.org/wiki/Uniform_Law_Commission