When Sam is trying to convince Josh to sue the white supremacists who shot him, Sam lists several court cases, including Brown v. Invisible Empire Knights of the Ku Klux Klan., Vietnamese Fisherman's Association v. the Knights of the KKK, and Donald v. United Klans of America. These are all real court cases brought and won by the Southern Poverty Law Center (a Montgomery, Alabama-based civil rights organization) against various racist, anti-semitic, and anti-immigrant groups on behalf of people (or survivors of people) who had been victims of those groups.
The title of this episode is taken from song "For He is an Englishman" (which is sung by the cast in the final scene of the episode) from Gilbert and Sullivan's operetta H.M.S. Pinafore. The actual line reads: "He is an Englishman/for he himself has said it/and it's greatly to his credit/That he is an Englishman".
Despite everybody's insistence that all of Gilbert and Sullivan's plays are about duty, the operetta H.M.S. Pinafore, which is frequently referred to in this episode, is mainly about differences in social class.
John Larroquette is correct in his statement that The Pirates of Penzance is about duty. The full title of The Pirates of Penzance is actually The Pirates of Penzance, or The Slave of Duty.
This is the second episode of "The West Wing" to have a character named Tribbey - in the first season episode "He Shall, from Time to Time... (2000)", Tribbey was the name of the Secretary of Agriculture who was picked to sit out the State of the Union.