In his concurring opinion, Justice Anthony Kennedy began by acknowledging the long history of the Court’s interpretation of the Commerce Clause, noting that the transition to a single, integrated national economy “counsels great restraint before the Court determines that the [Commerce] Clause is insufficient to support an exercise of the national power.” Kennedy explained that while this long history gives him “pause” about the Court’s decision, it’s the Court’s duty to intervene when the exercise of national power threatens to upset the fundamental federal-state balance, especially when a statute lacks an evident commercial nexus and intrudes upon an area of traditional state concern. 

In this case, Kennedy found the Gun Free School Zones Act to be unconstitutional because neither the regulated actors nor their conduct were of a commercial character. The statute criminalized the possession of a gun within 1,000 feet of a school, which is a clear intrusion on education, an area traditionally regulated by the States. Kennedy explained that while there is near universal agreement that guns don’t belong in schools, there’s considerable disagreement on the best policy methods to achieve that goal. He argued that by creating a uniform federal criminal prohibition and drawing an invisible boundary around over 100,000 local schools, the statute displaced state authority and foreclosed States from the chance to solve the problem. Kennedy argued that such an action prevents States from acting as “laboratories for experimentation” to devise localized solutions, which is an important part of the federalist system designed by the framers. 

In his concurring opinion, Justice Clarence Thomas explained that while he agreed with the Court’s ruling, he wrote separately because he believes that the Court’s case law had drifted far from the original understanding of the Commerce Clause. Thomas argued that at the time of the Constitution’s ratification, the term “commerce” strictly consisted of selling, buying, bartering, and transporting for those purposes, which is clearly different from productive activities like manufacturing and agriculture. Thomas posited that that the original understanding of Congress’ commerce power never encompassed the mere possession of a good or purely personal activities that are completely separated from business or trade. 

Thomas further argued that the Constitution didn’t support the idea that Congress possessed authority over any activity that “substantially affected” interstate commerce. Thomas explained that such a test rendered much of Article I, Section 8 “surplusage”, since if the Commerce Clause broadly covered anything with a substantial effect, there would have been no need for the framers to specifically enumerate other federal powers, such as the authority over bankruptcies or tax collection. He wrote, “if a ‘substantial effects’ test can be appended to the Commerce Clause, why not to every other power of the Federal Government? There is no reason for singling out the Commerce Clause for special treatment.” He noted that this broad interpretation was a twentieth-century innovation that wrongly departed from a century and a half of precedent. 

Lastly, Thomas criticized the “aggregation principle” embedded in the substantial effects test, arguing that it effectively granted the federal government a limitless police power over the nation. Thomas argued that by aggregating the effects of a class of activities, Congress could regulate entirely noncommercial and trivial human conduct by simply drawing a broad enough statutory circle. Because this framework lacked any principled stopping point and obliterated the distinction between national and local matters, Thomas concluded that the Court needed to temper its Commerce Clause jurisprudence in future cases and construct a standard more faithful to the Constitution’s original design of limited and enumerated powers. 

In his dissenting opinion, Justice Stephen Breyer argued that the Gun Free School Zones Act was well within Congress’ authority granted by the Commerce Clause and rested his argument on three basic principles. First, that the Commerce Clause encompassed the power to regulate local activities that significantly affected interstate commerce. Second, that the Court had to consider the cumulative effect of all similar instances, rather than just a single act of gun possession. Third, that the Court only needed to determine whether Congress had a “rational basis” for concluding that a significant factual connection existed between the regulated activity and interstate commerce. 

In this case, Breyer found that Congress possessed a rational basis for connecting gun-related school violence to interstate commerce. Breyer argued that widespread violence in schools significantly interfered with the quality of education, which impacts the economy. He explained that “[e]ducation, although far more than a matter of economics, has long been inextricably intertwined with the Nation’s economy.” 

Breyer also argued that gun violence near classrooms posed a serious economic threat by producing inadequately educated workers for the modern workforce and by depriving communities of a well-educated population. Breyer argued that since the connection between education and national economic well-being was uniquely significant, upholding the statute wouldn’t obliterate the distinction between national and local matters or grant the federal government a limitless police power over a traditionally state-controlled area. 

Breyer concluded with a warning that the majority’s holding created three serious legal problems. First, it ran contrary to modern precedents that had upheld congressional actions with even weaker connections to interstate commerce. Second, it relied on a formalistic and unworkable distinction between “commercial” and noncommercial activities, which revived a categorical approach the Court had previously abandoned. Third, it threatened to inject profound legal uncertainty into the law by casting doubt on numerous existing federal statutes that regulated noncommercial activities or lacked explicit jurisdictional elements. 

In his dissenting opinion, Justice John Paul Stevens argued that guns are “both articles of commerce and articles that can be used to restrain commerce” and that possession of them is the direct or indirect consequence of commercial activity. Stevens explained that in his opinion, “Congress’s power to regulate commerce in firearms includes the power to prohibit possession of guns at any location because of their potentially harmful use; it necessarily follows that Congress may also prohibit their possession in particular markets.” Stevens concluded with a note that “the market for the possession of handguns by school-age children is, distressingly, substantial. Whether or not the national interest in eliminating that market would have justified federal legislation in 1789, it surely does today.” 

In his dissenting opinion, Justice David Souter argued that the Court should’ve deferred to Congress’ implicit judgment that the regulated activity substantially affected interstate commerce so long as there was a “rational basis” for their legislative finding. Souter argued that the practice of deferring to rationally based legislative judgments was a vital paradigm of judicial restraint. By granting this leeway to the legislative branch, Souter explained that the Court properly respected both Congress’ institutional competence in areas expressly assigned to it by the Constitution and the democratic legitimacy derived from the legislature’s political accountability. 

Souter further argued that the Court’s decision ignored the lessons of history, noting that the modern respect for congressional primacy only developed after the Court’s experiences in the 1930s, when it was forced to repudiate an untenably expansive conception of judicial review. Souter criticized the majority’s distinction between “commercial” and “noncommercial” activities, comparing it directly to the old, unworkable distinction between “direct” and “indirect” effects on commerce. Souter argued that by calibrating the level of judicial deference based on whether an activity was patently commercial, the Court was reviving the same formalistic line-drawing that was done away with decades ago. Souter concluded with a warning that the decision would lead to a return to those old pitfalls and explained that he found no reason why the majority’s new qualification of rational basis review would be any more successful.