Introduction

Congress's Commerce Power

Introduction

When a federal statute is challenged in court, the first question the government must answer is where Congress found the power to enact it. The Constitution vests in Congress only the legislative powers "herein granted," so Congress can act only where some listed power supports the statute.¹ The States stand in the opposite position. They hold the general authority to govern, called the police power, and need no constitutional grant for most of what they do, while Congress has no such general power.² Dividing authority this way keeps either the nation or the States from accumulating unchecked power, which is why each listed power needs real edges.³ Of those powers, Congress relies most often on the Commerce Clause, which authorizes it "To regulate Commerce with foreign Nations, and among the several States, and with the Indian Tribes."⁴ Federal power over foreign commerce and commerce with the tribes is plenary and has no comparable state counterpart, so the hard doctrinal questions gather around commerce among the States.⁵ The Necessary and Proper Clause, which lets Congress make laws needed to carry its listed powers into execution, appears at the end of the same section and returns in later parts of this chapter.⁶

The first analytical question here is therefore a narrow one: does the regulated subject fall inside the commerce power at all? Whether the statute is wise belongs to the voters, and whether it infringes individual liberty is a separate inquiry that restrains federal and state governments alike. A simple test sorts the two kinds of doubt. Take a federal statute requiring motorcyclists to wear helmets and ask whether a state or city could enact the same rule. If the answer is no, the doubt concerns individual liberty. If the answer is yes, the only remaining doubt is whether Congress, rather than the States, holds the power to act, and that is the doubt this chapter addresses.⁷ The dormant Commerce Clause is also a different inquiry. It limits what States may do when their laws burden out-of-state competitors, and it is not covered here.⁸

On the power question, the answer is usually yes, and that is why the exceptions deserve close attention. From 1937 until 1995 the Supreme Court did not strike down a single federal statute as exceeding the commerce power.⁹ When the Court finally did so in United States v. Lopez, it reasoned that a reading of the clause with no outer edge would hand Congress the general police power the Constitution withholds.¹⁰ The doctrine is easiest to learn in the order it developed: the meaning of commerce, then the effects-based reasoning and aggregation that carry the power to local activity, then the three categories of regulable activity, and finally the decisions that mark where the power stops. That path begins with Chief Justice Marshall's definition of commerce in Gibbons v. Ogden, which the next section takes up.¹¹