A state can make anything legal it wants to, but if it goes against a federal ruling whether it be a court case, law, etc… it would not be legal as some may hope. As I said, state police won’t enforce the federal laws, and federal police won’t enforce state laws. They each enforce their respective law set, so state enforce state laws (meaning they won’t arrest you for pot in CO), and federal enforce federal laws (meaning they will arrest you for pot in CO).