The Constitution expressly authorizes Congress to "regulate Commerce with foreign Nations, and among the several States." However, it says nothing about the protection of interstate commerce absent any affirmative action by Congress. The Supreme Court has consistently recognized implicit in the language of the Commerce Clause "a further, negative command, known as the dormant Commerce Clause, prohibiting certain state taxation even when Congress has failed to legislate on the subject." In finding that states may constitutionally tax the local portion of interstate business transactions, the Court has held that "[it was not the purpose of the Commerce Clause to relieve those engaged in interstate commerce from their just share of state tax burden even though it increases the cost of doing business."' This concept is known as apportionment.
Jason P. Livingston,
Form v. Substance: The Supreme Court Retreats Into Its Formalistic Shell in Oklahoma Tax Commission v. Jefferson Lines,
U. Rich. L. Rev.
Available at: http://scholarship.richmond.edu/lawreview/vol29/iss5/8