The U.S. Supreme Court case Gaston County, North Carolina v. United States (1968) dealt with voting rights and racial discrimination in education. The court ruled that the literacy test used by Gaston County to determine voter eligibility was discriminatory against African Americans due to the county's history of segregated schooling which had provided substandard education for black citizens compared to their white counterparts. This ruling established a significant precedent: if a jurisdiction has maintained racially discriminatory schools, it cannot use educational attainment or literacy tests as prerequisites for voting because these requirements would disproportionately disenfranchise minority voters who were denied equal educational opportunities.

In the dissenting opinion for Gaston County, North Carolina v. United States (1968), Justice Harlan argued that the majority's decision to invalidate literacy tests as a voting requirement was an overreach of judicial power. He contended that Congress had not intended to prohibit all literacy tests when it passed the Voting Rights Act in 1965 but only those administered unfairly or discriminatorily. According to him, there was no evidence presented showing that Gaston County's test was discriminatory in nature or application; rather, it seemed designed and implemented with fairness and impartiality. Furthermore, he believed such decisions should be left up to local governments unless clear violations of federal law were evident. The majority’s ruling could potentially undermine states' rights by setting a precedent where any state policy indirectly affected by past discrimination could be invalidated without explicit Congressional intent.