Clause and effect: a Commerce Clause case may limit Congress's power.

Gun-ownership cases usually revolve around Second Amendment issues. But United States v. Lopez, currently under consideration by the Supreme Court, involves the 10th Amendment and the Constitution's Commerce Clause. Because Lopez may strongly limit Congress's ability to invoke its right to regulate interstate commerce, the decision may be one of the most far reaching in the post-New Deal era.

In 1992, Alfonso Lopez Jr., a 12th grader at Edison High School in San Antonio, Texas, broke the law by bringing a .38-caliber handgun to school. Although his action was illegal under Texas law, authorities charged Lopez with violating the federal Gun-Free School Zones Act of 1990. Lopez was convicted but appealed the decision on the grounds that the Gun-Free School Zones Act was unconstitutional.

Lopez's lawyers argued that the act invoked no delegated power of Congress for its authority. The government countered that the act was a legitimate exercise of Congress's constitutional power to regulate interstate commerce. The Fifth Circuit Court of Appeals ruled that the statute was outside the commerce power of Congress and an infringement of the 10th Amendment. The court also concluded that Congress could regulate intrastate activity only when it had a "substantial economic effect on interstate commerce."

"Our understanding," wrote the court, "of the breadth of Congress' commerce power is related to the degree to which its enactments raise Tenth Amendment concerns, that is concerns for the meaningful jurisdiction reserved to the states....[T]he Tenth Amendment, though it does not purport to define the limits of the commerce power, obviously proceeds on the assumption that the reach of that power is not unlimited, else there would be nothing on which the Tenth Amendment could operate."

If the Supreme Court strongly affirms the appeals court decision in Lopez and limits the use of the Commerce Clause to laws actually dealing substantially with interstate commerce, the impact on the proliferation of federal criminal laws and regulations will be huge, says University of Tennessee law professor Glenn Harlan Reynolds. "Many of those laws and regulations won't be sustainable if the Court cuts back the Commerce Clause to something close to its original meaning," says Reynolds. The Supreme Court, which heard arguments in the case last fall, is expected to issue its decision late this spring.