Taxing and Spending Clause
Indirect taxes are subject to the rule of uniformity. This states "all Duties, Imposts and Excises shall be uniform throughout the United States". At first, the Supreme court declared that a tax is uniform "if it "operates with the same force and effect in every place where the subject of it is found." In United States v. Ptasynski (1983), the Court concluded unanimously that any tax in which the subject is defined in non-geographic terms satisfies the Uniformity Clause. Secondly, where a subject is defined geographically, the tax needs to carefully look for any "actual geographic discrimination."