I have been studying the US constitution lately, and an excerpt from Article 1 Section 10 seems appropriate: 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 its 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 Unites States; and all such Laws shall be subject to the Revision and Control of the Congress. In liberty, Peter Baumbach