And under threat of imprisonment in a state prison! Wyoming's FFA has such a provision, as does New Hampshire's (though the NH one hasn't been enacted yet).
Do you have a link for that? When I read the statute, and its history, I saw that Montana had initially stated it would defend a Montana citizen in federal court, if the feds attempted to enforce federal law over the Montana law. That provision (just to use the Montana AG to defend its own law) was removed before the Montana law was enacted.