In what circumstances have courts intervened on equal protection grounds?

The second major area in which, applying strict scrutiny, the courts have intervened on equal protection grounds is where state geographical districting systems dilute the effectiveness of the franchise either directly or through the allocation of legislative representation. (E.g. Reynolds v. Sims, supra, 377 U.S. 533, 84 S.Ct. 1362, 12 L.Ed.2d 506 [involving malapportionment of state legislatures and applying the "one man one vote" rule to legislative apportionment].)