"Preemption" is a legal term for the federal government's ability to trump, supersede, or displace state and local laws. But it is often unclear when and how federal regulation displaces a particular state law--often a literal billion-dollar question.

In a new book, Federal Preemption: States' Powers, National Interests (AEI Press, May 2007), edited by Richard A. Epstein and Michael S. Greve and based on papers presented at an AEI conference in April 2006, noted legal scholars and lawyers discuss this concept. In the introduction, Epstein and Greve set the tone, explaining that the debate should be informed by an understanding of the constitutional and structural issues at stake, as well as by the details of specific statutes.

The first section of the book provides an historical context for federal preemption. Viet D. Dinh lays out the nineteenth-century legal framework, and Stephen A. Gardbaum carries the story through the early twentieth century and into the New Deal. Together, the authors chronicle how the young American republic developed its understanding of federalism and adapted it to changes in circumstance and ideology.

The authors of the essays in part II consider the workings of federal preemption today, exploring the complicated relationship among federal and state laws, regulatory rulings, and common law in a variety of contexts. Daniel E. Troy argues that drugs and drug labels approved by the Food and Drug Administration should not be vulnerable to state tort law. Thomas W. Hazlett writes that the preemption of state cell phone regulation was efficient and should be expanded, and Hal S. Scott concurs in the case of financial services regulation. Thomas W. Merrill addresses preemption issues in environmental regulation, and Samuel Issacharoff and Catherine M. Sharkey focus on product liability law.

The final section returns to broader themes. Robert R. Gasaway and Ashley C. Parrish formulate systematic, non-arbitrary distinctions between areas in which state regulatory activity is permitted and those in which it is proscribed. Ernest A. Young examines the relationship between federalism and preemption, focusing on issues of state autonomy. Anne van Aaken offers an international perspective, comparing and contrasting the European Union's preemption practices with those of the United States.

In their conclusion to Federal Preemption, Epstein and Greve share their own analysis in light of the contributors' arguments. Preemption analysis, they say, should be informed by three interpretive presumptions that are rooted in the constitutional structure: an "anti-circumvention principle" that protects statutory integrity against the ever-present risk of state evasion; a presumption for exclusive rather than concurrent state and federal authorities; and a pro-preemption presumption for federal statutes that seek to curb federalism's coordination problems--economic balkanization, state protectionism, and interstate aggression and externalities.

For more information about this book, visit www.aei.org/book885/. For more information about AEI's Federalism Project, visit www.federalismproject.org. Epstein and Greve will discuss Federal Preemption at a June 12 AEI book forum.