In 1970 Harper received his law degree from the University of South Carolina where he specialized in constitutional law. He was the second African-American to graduate from the law school.
Harper was one of the first Blacks elected to the Richland County Council and the only Black to win a Democratic Party at large runoff election in 1978. As lead counsel for the South Carolina NAACP, he fought for equal political representation and voting rights in the state.
These proceedings led to the election of Congressman James Clyburn, the first Black congressman from the state since Reconstruction as well as the election of eight Black state senators and 26 Black state representatives. Many other Black elected officials at state, county and local levels obtained those positions as a result of his work.