Smith v. Allwright
Smith v. Allwright, 321 U.S. 649 (1944) was an important decision of the United States Supreme Court with regard to voting rights and, by extension, racial desegregation.
Smith, a black voter in a Southern state, sued for the right to vote in a primary election being conducted by the Democratic Party. The law he challenged allowed the party to enforce a rule requring all voters in its primary to be white. At this point in history, the Republican Party was so weak that most Southern elections were decided by the outcome of the Democratic primary. Smith said that the law in question essentially disenfranchised him by denying him the ability to vote in what was essentially the only meaningful election in his jurisdiction; the Court agreed and found in his favor. Many felt that this set the stage for the decision in Brown v. Board of Education, 347 U.S. 483 (1954) ten years later and helped lead the way into the Civil Rights Era.
Many Southern politicians of the era who are now largely regarded as progressive nonetheless were staunch supporters of the "white primary", perhaps most notably J. William Fulbright.