The populations of state legislative districts must be as equal as mathematically possible so as to ensure equal protection. Decided June 15, 1964 (argued November, 1963). Opinion of the Court: Earl Warren → go there Dissenting: Harlan. Applied: the Fourteenth Amendment → go there Topic: Voting and redistricting. Reynolds v. Sims, 377 U.S. 533 (1964), was a landmark United States Supreme Court case in which the Court ruled that the single-seat electoral districts of state legislative chambers must be roughly equal in population. Along with Baker v. Carr (1962) and Wesberry v. Sanders (1964), it was part of a series of Warren Court cases that applied the principle of "one man, one vote]]" to U.S. legislative bodies. Wiki link