> That’s the purpose of the Supreme Court: a check on the legislature and executive branches.
This is correct, but not intended to be the source of law(1). In fact, Supreme Court decisions aren't a law per se, but a deterrent in creating legally questionable situations.
(1)A Supreme Court decision is made moot by legislation, as per any law, but the deterrent is significantly weaker in practice than a written law as it's scrutinized more closely as a matter of interpretation, court makeup, and public opinion.
> (1)A Supreme Court decision is made moot by legislation, as per any law
Minor nitpick: Not all decisions can be overridden by law. Cases dealing with constitutionality particularly. If the Supreme Court says something is a Constitutional right, only two things can overturn it: (1) a Constitutional Amendment, and (2) another Supreme Court decision[a].
[a] Brown v. Board, for example, overturned Plessy v. Ferguson[b]
[b] Well, not exactly. They didn’t say they were overturning that decision, but it made the old one moot by saying the opposite of it (leading to the same result).
A Constitutional Amendment is an "amendment" to a law (the Constitbution), although I would say that's the same as any other law insofar as it's a sum of written parts. Also, SC decisions are generally limited in some context, so there's no "need" to amend over it, as long as you can challenge again under a different political climate (court makeup or public opinion).
Since Hammurabi.