There are many state laws that contradict a federal law. But they have to actually be challenged by a federal court in order to be nullified. States can make

There are many state laws that contradict a federal law. But they have to actually be challenged by a federal court in order to be nullified. States can make up all the hair-brained laws they want but if they never get sued by the feds then nobody cares. For instance, all the states legalizing marijuana right now in defiance of federal law.