There has been at least one thread with discussion of the seemingly redundent title of Klingon Imperial Empire. https://www.trekbbs.com/threads/the-klingon-imperial-empire.277384 Some people don't think that it is redundent to write about an imperial empire. https://www.quora.com/Did-the-Imperial-Japanese-Empire-ever-win-battles-against-the-American-Empire Possibly there is some connection with the movie title mentioned in an earlier post. ↑ I think what Ronald D. Moore may have had in mind here by adding the seemingly redundant word "Imperial" to Klingon Empire was a nod to what the Japanese called their empire: Dai Nippon Teikoku, literally Greater Japanese Empire. There was an infamous Japanese WWII film released in 1982 with that exact title (Dai Nippon Teikoku) which was a defense of Japanese Imperialism. The U.S. title was translated as The Imperial Japanese Empire. It's just a guess on my part, but it's certainly within the realm of possibility that Moore thought of this film (or the translation) while writing the teleplay for "Sins of the Father."