Quite a few people are pushing the idea that states may and should "nullify" -- refuse to cooperate with, or resist as necessary -- unconstitutional federal statutes. Many of these people nominate Obamacare as a current example. Often, the response is that nullification violates the U.S. Constitution.
You can drop by The Hoosier Gadfly's recent post on this subject -- if you have time for a thorough exposition. If not, here's a short summary: Thomas Jefferson and James Madison believed otherwise, based on (in part) the reasoning that the federal government -- no matter which branch -- can't be the sole judge of the constitutionality of its own actions. Also, Article VI requires all state officials to swear or affirm to support the Constitution. If your response is that this means to follow the U.S. Supreme Court's interpretation of said Constitution, see the previous point -- and also, the following thought experiment.
The constitutional provision that establishes the U.S. Supreme Court and gives Congress the power to set up lower federal courts -- Article III -- also says, explicitly, that the Supreme Court has appellate jurisdiction (the power to review) "with such Exceptions, and under such Regulations as the Congress shall make." No amendment to the Constitution has monkeyed with this language. What this means is that Congress has the power to insulate its own statutes from Supreme Court scrutiny. If I correctly read Andrew Gold's article on how the Court has interpreted this clause, the Court has not entirely accepted that Congress may retroactively remove the Court's power to review previously passed statutes -- but otherwise does acknowledge that power, and further, that Congress' motives in taking such action are essentially irrelevant. (By the way, there's considerably less textual basis for the Supreme Court's power to invalidate any Congressional action, a power which was not universally conceded prior to the 1803 case of Marbury v. Madison.
So: let's postulate that Congress passes legislation providing that anyone insulting the President has committed the crime of undermining the stability of the government (Alien and Sedition Acts redux, more or less), and must be arrested by state police and thrown in the state hoosegow. Not only does this blatantly violate the First Amendment, but it's federal mandate enlisting state officials without requiring their consent, which would appear to violate U.S. Supreme Court precedent. However, Congress cleverly includes in this legislation a provision prospectively eliminating the Supreme Court's jurisdiction to review cases arising from the new statute. So the Supremes will not be riding to the rescue.
Under these circumstances, is the First Amendment dead, and the citizenry helpless? Or could the states refuse to perform their new and unconstitutional duties?
(a) That's nullification, folks.
(b) Where is the textual basis for confining this state power to the circumstances I've described?
(Bar examiners, feel free to borrow this hypothetical for use in bar exams.)