A 1789 Congressional statute provided that 'all pilots in the bays, inlets, rivers, harbors, and ports in the United States shall continue to be regulated in conformity with the existing laws of the states, respectively, wherein such pilots may be, or with such laws as the states may respectively hereafter enact for the purpose, until further legislative provision shall be made by Congress.' A Pennsylvania law of 1803 required ships entering or leaving the port of Philadelphia to engage a local pilot to guide them through the harbor, and imposed a penalty for noncompliance. State courts upheld imposition of the penalty on Cooley (P). P challenged the law contending that the commerce clause gave Congress exclusive jurisdiction over commerce. Therefore, Congress could not regrant its authority to Pennsylvania and any state law would be void.