>It's constitutional because the Supreme Court ruled it was in the case Train v NYC. They are the ones who determine what laws are constitutional or not. You can disagree but their opinion is what is acted upon.
We're going in circles, I already addressed this.
>The president must sign spending bills and while he may be overridden with a veto that's the check and balance.
The powers not delegated to the United States by the Constitution, nor prohibited by it to the States, are reserved to the States respectively, or to the people
POTUS has no power to execute an unconstitutional law
1. I said "Where does it say he doesn't have to [enforce a law] if it violates the Constitution?"
2. You pasted the 10th amendment - This says the federal government has the powers specified by the constitution and any power not mentioned are for the states unless prohibited
3. Then I asked you how this related to the president not enforcing laws he believes are unconstitutional and you said "If the "United States [government]" doesn't have the power, POTUS in his official capacity doesn't."
We're going in circles, I already addressed this.
>The president must sign spending bills and while he may be overridden with a veto that's the check and balance.
That's a check and balance.