Article I, Section 10, Clause 2:
No State shall, without the Consent of the Congress, lay any Imposts or Duties on Imports or Exports, except what may be absolutely necessary for executing it's inspection Laws: and the net Produce of all Duties and Imposts, laid by any State on Imports or Exports, shall be for the Use of the Treasury of the United States; and all such Laws shall be subject to the Revision and Controul of the Congress.
Overruling a line of prior decisions that it thought misinterpreted the language of Brown v. Maryland, the Court now holds that the clause does not prevent a state from levying a nondiscriminatory, ad valorem property tax upon goods that are no longer in import transit. 1 Thus, a company's inventory of imported tires maintained at its whole distribution warehouse could be included in the state's tax upon the entire inventory. The clause does not prohibit every
tax with some impact upon imports or exports but reaches rather exactions directed only at imports or exports or commercial activity therein as such. 2