In the general sense, let's say a state law is passed, and the courts decide that the law is unconstitutional because the United States constitution prohibits such laws. Can a state amend its own constitution to allow the law; or would that not help because it still violates the US constitution?
For a specific example, North Carolina passed a voter ID law which was struck down by the courts, finding that the law was created with the intent of targeting African Americans and suppressing their votes. I was unable to find more specific constitutional reasoning given, but it seems like this would be a 14th amendment issue; that the law was shown to deprive certain classes of citizens of their rights.
Now, in the upcoming election, North Carolina has a ballot initiative to add an amendment to the NC State Constitution to require an id to vote. However, would such an amendment even be allowed; if it could still be found to violate the US Constitution's 14th amendment?
Or, can a state's constitution override the US constitution in these matters?