United States v. Lopez is familiar to everyone who teaches constitutional law. It leads off the section on the commerce clause in many casebooks and serves as a "master case" in the sense that it discusses and categorizes many other prior cases. Lopez was remarkable when it was decided, for it was the first time in nearly 60 years that the Supreme Court had struck down a congressional statute on the basis that it was beyond Congress's power to regulate interstate commerce. Justice Breyer wrote the principal dissent and he discusses Lopez in his new book, Making Our Democracy Work.

Lopez struck down the Gun-Free School Zones Act of 1990, which made it a federal crime to possess a firearm in a school zone. While the decision may have surprised some members of Congress, many commentators at the time saw the Act as something of a stretch. The relevant test was whether the activity regulated by the act substantially affected interstate commerce. The test could be posed as a practical question. If someone carried a gun to school, how did that have anything to do with interstate commerce? Even reasonably liberal legal scholars defended the Court's opinion, written by Chief Justice Rehnquist. Rehnquist used a slippery slope argument – if Congress could regulate the mere possession of a gun in a particular place, what activity would be beyond Congress's reach? He posed a challenge for Breyer along this line, asking Breyer to specify the outer limits of congressional authority.

Arguably this missed the point of Breyer's dissent. Breyer reemphasizes his essential arguments in the book. He saw the case as posing an institutional (rather than interpretive) challenge because it involved the tangled issues surrounding federalism, the determination of what is truly local (intrastate and beyond Congress's power) and what is national (interstate). He remarks that Lopez "was difficult to decide largely because of the factual interconnections that underlay the Court's judgment, as they often do where legal questions involving federalism are at issue." Harmful substances and activities can have strong local and national effects at the same time. How should we decide which branch of government should step in and regulate? Breyer observes that "there is rarely an easy answer to the question of what level of government should be primarily responsible for helping to resolve the problems that potentially call for legislation." This is a job better suited for legislators than justices.

This is the sort of reasoning lawyers became familiar with after the New Deal. So why did the Court deviate from it? I recall a lecture Justice Scalia gave at Tulane after Lopez and the later case of U.S. v. Morrison were decided. Scalia defended the Court against the charge that these decisions were "activist." He said all the Court was doing was intervening to get rid of some "weird laws" passed by Congress. The Court was simply policing the boundaries of the Constitution. But how effective was its intervention? At the end of the Lopez opinion, Rehnquist provided this summary of the Court's reasoning: "The possession of a gun in a local school zone is in no sense an economic activity that might, through repetition elsewhere, substantially affect any sort of interstate commerce. Respondent was a local student at a local school; there is no indication that he had recently moved in interstate commerce, and there is no requirement that his possession of the firearm have any concrete tie to interstate commerce." The last two observations undermined the supposedly clear requirement of "economic activity." Suppose Lopez had moved in interstate commerce or his firearm had?

Time has shown Breyer's dissent to be correct (a point further reinforced by the outcome in Gonzales v. Raich). Surveys showed that lower federal courts were not able to apply the Lopez test and it made no concrete difference to congressional power. As Breyer observes in his book: "Consequently, and not surprisingly, the Court's decision in the gun case did not stop Congress from reenacting a virtually identical statute. This time the statute applied its strictures only to guns that had moved in, not just affected, interstate commerce. And virtually every gun satisfies that condition." In Breyer's view, the "fact-based nature of the problem," that is, the proper division between what is local and what is national, is not one best suited for courts. While principles can be articulated, workable principles that will restrain Congress in some "proper" way are not available. Justice Breyer suggests that we should concern ourselves with what works.