actually its not how can the state law violate federal law.. its how can federal go in and under mind state law... the reason we had the civil war it was because in the constitution it says that federal law will not trump state law ie. states have slaves and some states dont and so they were fighting for federal law to not come in and under mind state but the south lost and federal government gets to do what ever it wants now.. and if you dont believe me look it up.... thats why it is bull shit when in cali it is legal to have weed banks (i dont know the real name) and the DEA come in and arrest every one...