Stephen Johnson Field

“ In conferring upon congress the regulation of commerce, it was never intended to cut the states off from legislating on all subjects relating to the health, life, and safety of their citizens, though the legislation might indirectly affect the commerce of the country. Legislation, in a great variety of ways, may affect commerce and persons engaged in it without constituting a regulation of it within the meaning of the constitution. ”

“ The tax, duty, impost, or toll thus referred to and thus prohibited are such as are directed against the commerce of the rivers, and not such as are imposed by any regulation for convenience in the measurement or storage of coal or coke carried. The freedom contemplated is that which would be destroyed by denying equality of rights to any particular class of vessles or mode of navigating the Mississippi and other rivers leading into the Gulf of Mexico. All such rivers are to be deemed highways, and equally open to all persons who choose to pursue commerce upon them. ”

“ To draw the line of interference between the two fields of jurisdiction, and to define and declare the instances of unconstitutional encroachment, is a judicial question often of much difficulty, the solution of which, perhaps, is not to be found in any single and exact rule of decision. ”