The Congress shall have power to … fix the Standard of Weights and Measures …The Congress, not a foreign body such as the International Bureau of Weights and Measures (headquarters Paris, France). Never mind who controls what is now known as coordinated universal time (UTC), that being the International Telecommunications Union, control of which was handed over to the UN in 1949.
— US Constitution, Article I, Section 8, Clause 5
Your first sentence is a sentence fragment you have the subject but you don’t say what it should be doing.
So we should have our clocks and weights and whatever be different than everybody else out of sheer cussedness? Seems perfectly reasonable for Congress to say “we’ll use the international standards”.