The 'compelling interest' doctrine constitutes an increasingly significant exception to the long-established rule that a statute does not deny equal protection if it is rationally related to a legitimate governmental objective. The 'compelling interest' doctrine has two branches. The branch which requires that classifications based upon 'suspect' criteria be supported by a compelling interest apparently had its genesis in cases involving racial classifications, which have, at least since Korematsu v. United States, 323 U.S. 214, 216 (1944), been regarded as inherently 'suspect.' See Loving v. Virginia, 388 U. S. 1, 388 U. S. 11 (1967); cf. Bolling v. Sharpe, 347 U. S. 497, 347 U. S. 499 (1954). See also Hirabayashi v. United States, 320 U. S. 81, 320 U. S. 100 (1943); Yick Wo v. Hopkins, 118 U. S. 356 (1886). The criterion of 'wealth' apparently was added to the list of 'suspects' as an alternative justification for the rationale in Harper v. Virginia Bd. of Elections, 383 U.S. 663, 668 (1966), in which Virginia's poll tax was struck down. The criterion of political allegiance may have been added in Williams v. Rhodes, 393 U.S. 23 (1968). See 394 U. S. 9, infra. ...