http://legal-dictionary.thefreedictionary.com/standing

A significant economic injury or burden is sufficient to provide standing to sue, but in most situations a taxpayer does not have standing to challenge policies or programs that she is forced to support. In Frothingham v. Mellon, 288 F. 252 (C.A.D.C. 1923), the Supreme Court denied a federal taxpayer the right to challenge a federal program that she claimed violated the Tenth Amendment, which reserves certain powers to the states. The Court said that a party must show some "direct injury as the result of the statute's enforcement, and not merely that he suffers in some indefinite way common with people generally."

Although the Supreme Court made a narrow exception to this prohibition on taxpayer suits in Flast v. Cohen, 392 U.S. 83, 88 S. Ct. 1942, 20 L. Ed. 2d 947 (1968), granting standing to a taxpayer to challenge federal spending that would benefit parochial schools, the Court has never gone beyond that. In fact, there is some doubt as to the vitality of the Flast decision. In 1974 the Court denied standing to a taxpayer who sought to challenge Congress's exempting the Central Intelligence Agency from the constitutional requirement under Article I, Section 9, Clause 7, that government expenditures be publicly reported (United States v. Richardson, 418 U.S. 166, 94 S. Ct. 2940, 41 L. Ed. 2d 678). Since Richardson the Court has continued to maintain the traditional barrier against taxpayer lawsuits.