III. The Power to Regulate Commerce

The commerce clause has been a double-edged tool of constitutional interpretation from the earliest days of judicial review of state and federal legislative activity. It is at once a positive source of federal power and, in the absence of federal exercise of that power, a source of implied limitations on state legislation. Any consideration of trends of interpretation of the clause in the past decade must treat both aspects of the matter. In general, it may be said that expansive implications of the Wagner Act decisions in the spring of 1937 have been elaborated and broadened until the commerce clause is today an ample source of federal legislative authority to deal with a wide range of problems arising out of or having any substantial effect upon interstate commerce. No such clear generalization may be made with respect to the nature of the limitations which the unexercised commerce power imposes on state police power and tax legislation. But the tendency, not yet consistently dominant, seems to be in the direction of upholding much state legislation that would formerly have been ruled a burden on interstate commerce. It is, of course, unnecessary to labor the fact that state legislation incompatible with a valid federal exercise of the commerce power is unconstitutional. Both the above generalizations require some further examination. The first can perhaps best be looked at in terms of (1) changing definitions of interstate commerce, (2) the reshaping of familiar formulæ for determining the reach of the power to regulate, (3) the abandonment of the “dual federalism” concept, and (4) the broad application of federal statutes to businesses alleged not to be in interstate commerce. Discussion of the second general problem may perhaps best be considered in terms of the gradual, and still wavering, emergence of what may be called the “leaveit-to-Congress trend” in the review of state legislation alleged to burden interstate commerce.