Selective exclusiveness, or the Cooley doctrine, derives from the opinion of Justice benjamin r. curtis for the Supreme Court in cooley v. board of port wardens (1852). Before that case, conflict and confusion characterized the Court's decisions in commerce clause cases. Some Justices believed that Congress's power to regulate interstate and foreign commerce was an exclusive power and others that the states shared concurrent power over commerce. Some believed that a distinction existed between the national power over commerce and the state police power.
Cooley provided a compromise doctrine that transformed judicial thinking. The Court recognized that commerce embraces a vast field of diverse subjects, some demanding a single uniform rule that only Congress might make, and others best served by state regulations based on local needs and differences. Thus the doctrine treated congressional power as exclusive on a selective basis—in only those cases requiring uniform legislation; and the states shared a concurrent power in other cases. In cases of conflict, of course, congressional action would prevail.
The Cooley formulation necessarily failed to provide a means by which the Court could discern which subjects were national and which local. Accordingly the Justices were able to manipulate the doctrine to sustain or invalidate state legislation as they wished. In time, judicial analysis focused on the purposes of the legislation and the degree to which it adversely affected the flow of commerce, rather than on the nature of the subject regulated. No formulation could diminish the free play of judicial discretion.
Leonard W. Levy