The Supreme Court is not the ultimate decider of what the layman's document means. It was wrong when it decided, for instance, Plessy v. Ferguson. The law that the Court upheld patently violated the Fourteenth Amendment and was unconstitutional. The Supreme Court was simply wrong.
By definition, the Supreme Court does decide what is Constitutional. It doesn't decide what is right or moral, but it does, according to the Constitution, decide what laws conform to the Constitution.
That is their job, yes. But they don't always do their job, especially in a compromised government. Let's not pretend that Trump didn't stack the courts.
The Supreme Court is not the ultimate decider of what the layman's document means. It was wrong when it decided, for instance, Plessy v. Ferguson. The law that the Court upheld patently violated the Fourteenth Amendment and was unconstitutional. The Supreme Court was simply wrong.