During the early 1940s, he participated in voter-registration drives and raised funds for lawsuits against the white primary. Sweatt had an opportunity to write several columns for the Houston "Informer", thanks to Sweatt's father's friend, black Dallas publisher Carter W. Wesley. Post offices stopped promoting blacks to supervisory positions by systematically excluding them from clerical positions which would make them eligible to be promoted. Being a local secretary of the National Alliance of Postal Employees, Sweatt was concerned with discrimination and challenged these practices. While preparing documentation for this case with an attorney, he became more interested in the law. A few years later, in the mid-1940s, Sweatt decided to attend law school and asked William J. Durham to help him. Since Durham knew Texas didn't have law schools for blacks, he advised Sweatt to apply to the University of Texas School of Law. Sweatt not only sought admission but, responding to an appeal Lulu White made to a group of Houston blacks for a volunteer to file a lawsuit, also agreed to serve as the NAACP's plaintiff if he was rejected on the basis of race.