There is a specific and direct legal means for States to do that. It's called nullification.
Several of them already have legislation in place on that very issue, such as Virginia. Others have taken related matters and steps in hand, such as Arizona's immigration law.
What happens if the federal government tries to push past nullification or usurp that state's sovereignty? Well, that depends on how principled that State and it's leaders are.
I am watching Arizona along those same lines now. However, the final means of a State resisting federal abuse, beyond that even of nullification, is secession.
I only hope Alabama (
and other liberty loving states) live's up to it's motto ...
Audemus Jura Nostra Defendere. That is, "We dare defend our rights".