How would the US federal government respond to a state government's flat-out rejection of a particular federal law or judgment?

What would happen if the state legislature were, in an act of possible political suicide, to say, “Nuts to your ruling, federal judge,” and carry on ignoring?

See, many states have legislation in place to defend a traditional, heterosexual definition of marriage, sometimes as strong as an amendment to the state constitution.
Several such states, in particular Ohio and Utah (and eventually, Indiana) have been told by federal courts that their laws are unconstitutional, and via legal hocus pocus this means that the state must now legally recognize same-sex marriage.