Complex sentence: Prior to his work at "Slate", he worked as a paralegal for the Department of Justice, which he disliked, switching to journalism and serving as a writer and editor for the "Washington City Paper".
Split into simpler sentences: Prior to his work at "Slate", he worked as a paralegal for the Department of Justice, which he disliked, switching to journalism. Thereafter, he served as a writer and editor for the "Washington City Paper".