[Lurking Libertarian]

Does the Supreme Court have the authority to invalidate a state constitution?

Yes, under the Supremacy Clause, the federal Constitution trumps "anything in the Constitution or Laws of any State." Brown v. Board of Education, for example, invalidated several state constitutions which required school segregation.

[porter_knorr]

ok...
(but) doesn’t a new law have to be implemented? In order to be enforced?