The Harper v. Virginia Board of Elections case in 1965 was a landmark decision by the U.S Supreme Court that ruled poll taxes were unconstitutional under the Equal Protection Clause of the Fourteenth Amendment. The plaintiffs, Annie E. Harper and others, challenged Virginia's poll tax on grounds that it violated their rights to equal protection under law as provided for by the Constitution. They argued that this tax effectively disenfranchised poor voters who could not afford to pay it, thereby creating inequality in voting access based on wealth or income status. The court agreed with them and held that state laws requiring payment of such a tax as a precondition for voting were discriminatory and therefore unconstitutional. This ruling significantly expanded voter eligibility across Southern states where these taxes had been used as tools to suppress African American voters during Jim Crow era.

In the dissenting opinion for Harper et al. v. Virginia Board of Elections et al., Justice John Marshall Harlan II argued that the majority had overstepped its bounds by imposing a federal standard on what was traditionally a state issue, namely voting qualifications. He contended that there was no constitutional basis to declare poll taxes unconstitutional and believed it should be left up to individual states to decide whether or not they wanted such measures in place. Furthermore, he asserted that this decision could potentially open the door for further judicial interference in areas typically reserved for state control, which would undermine federalism principles inherent within American governance system.