Preemption starts off easy: Under the Supremacy Clause, federal laws take precedence over state laws. When a state law is inconsistent with federal law (whether in statutes, treaties, court decisions, or the Constitution), the state law gives way to the federal.
That may be the only easy thing about the doctrine. Figuring out what counts as a federal/state conflict, and then determining how broadly preemptive the federal law should be, can be very tricky.
Case in point: the federal laws that regulate drug and medical devices. Should the fact that a manufacturer has jumped through the hurdles of the federal Food, Drug and Cosmetic Act ("FDCA") to prove the safety and efficacy of its drug or device mean that an injured plaintiff cannot sue the manufacturer under state tort law, on the theory that "regulation" of these manufacturers by state tort law should be deemed preempted by the federal statutory regulation of drugs and devices that is already in place? With devices, it's particularly tricky, because medical devices are assisgned to "classes" based upon their potential harm to the user. Class I devices present the least potential harm and are subject to the least regulatory control. Class III devices, on the other hand, go through the most exacting level of agency regulation. When it comes to preemption of state tort law, different levels of regulation might very well be viewed in a different light and produce different results.
In 1996, the Supreme Court had an opportunity to consider the preemptive effect of federal law in a Class III device case. In Medtronic v. Lohr, the Court had to figure out the preemptive effect of language added to the FDCA by the Medical Device Amendments of 1976:
Except as provided in subsection (b) of this section, no State or political subdivision of a State may establish or continue in effect with respect to a device intended for human use any requirement (1) which is different from, or in addition to, any requirement applicable under this chapter to the device, and (2) which relates to the safety or effectiveness of the device or to any other matter included in a requirement applicable to the device under this chapter.The Court concluded that -- despite the relative rigor with which Class III devices are regulated -- the federal statutory language did not preempt state-law claims for negligent design, negligent manufacture, and failure to warn. Primary among the the Court's reasons was the absence of any federal cause of action for injured consumers, so that acceptance of the manufacturers' argument that state law claims are preempted would have left plaintiffs with no remedy whatsoever. It was also important to the Court that with respect to the device involved in this case, Medtronic did not actually go through the high hurdles of Class III regulation, because it successfully claimed that its device was "substantially equivalent" to other peviously approved devices.
Since 1996, the FDA has taken the position that federal law is not broadly preemptive when it comes to state laws that would hold manufacturers to a higher standard than the federal one -- in effect arguing that federal law sets a floor when it comes to design, manufacturing practices, and labeling, but not a ceiling. Starting in 2002, however, the Bush Administration has taken the position that federal law is broadly preemptive and sets both a floor and a ceiling. The result of this shift can be seen in opinions like the Third Circuit's last Tuesday in Horn v. Thoratec Corp. (No. 02-4597), in which the court -- relying heavily on a brief filed by the Bush Administration as friend of the court -- concluded that Medtronic was not controlling precedent and the plaintiff's state tort claims were preempted by the federal law. The principal reason for dissing Medtronic was the fact that the device in the Horn case had in fact gone through the rigorous pre-market approval process for Class III devices rather than rely on the generic requirements that apply to devices that seek marketing approval under the "substantial equivalence" test.
Although this distinction appears to have been on the Supreme Court's mind in Medtronic and has much to recommend itself as a matter of statutory text and regulatory policy, its broad application to claims such as Mrs. Horn's (and numerous other plaintiffs who have been bounced out of court by the Bush Administration's zealous advocacy on behalf of manufacturers) represents a new chapter in the Bush Administration's pursuit of "tort reform," a chapter that leaves many injured patients and their survivors with no relief at all. "Compassionate conservatism"? Hah! Meanwhile, you can read about the shift and its political implications in a good article by Robert Pear in today's New York Times.