<P> In Lassiter v. Northampton County Board of Elections (1959), the U.S. Supreme Court held that literacy tests were not necessarily violations of Equal Protection Clause of the Fourteenth Amendment nor of the Fifteenth Amendment . Southern states abandoned the literacy test only when forced to do so by federal legislation in the 1960s . The Civil Rights Act of 1964 provided that literacy tests used as a qualification for voting in federal elections be administered wholly in writing and only to persons who had completed six years of formal education . </P> <P> In part to curtail the use of literacy tests, Congress enacted the Voting Rights Act of 1965 . The Act prohibited jurisdictions from administering literacy tests to citizens who attained a sixth - grade education in an American school in which the predominant language was Spanish, such as schools in Puerto Rico . The Supreme Court upheld this provision in Katzenbach v. Morgan (1966). Although the Court had earlier held in Lassiter that literacy tests did not violate the Fourteenth Amendment, in Morgan the Court held that Congress could enforce Fourteenth Amendment rights--such as the right to vote--by prohibiting conduct it deemed to interfere with such rights, even if that conduct may not be independently unconstitutional . </P> <P> As originally enacted, the Voting Rights Act also suspended the use of literacy tests in all jurisdictions in which less than 50% of voting - age residents were registered as of November 1, 1964, or had voted in the 1964 presidential election . In 1970, Congress amended the Act and expanded the ban on literacy tests to the entire country . The Supreme Court then upheld the ban as constitutional in Oregon v. Mitchell (1970), but just for federal elections . The Court was deeply divided in this case, and a majority of justices did not agree on a rationale for the holding . </P> <P> The literacy test was a device to restrict the total number of immigrants while not offending the large element of ethnic voters . The "old" immigration (British, Irish, German, Scandinavian) had fallen off and was replaced by a "new" immigration from Italy, Russia and other points in Southern and eastern Europe . The "old" immigrants were voters and strongly approved of restricting the "new" immigrants . All groups of American voters strongly opposed Chinese and Asian immigration . The 1896 Republican platform called for a literacy test . </P>

When did congress outlaw literacy tests altogether as a prerequisite to voter registration