TASK DEFINITION: You will be given a trivia clue, and the category it belongs to. You should answer with the best answer that belongs in the category and is described by the clue. For simplicity, answers should be in all lower cased letters.
PROBLEM: Category: PEN NAMES 
Clue: He came out of "The Jungle" to write juvenile novels as Clarke Fitch

SOLUTION: upton sinclair

PROBLEM: Category: LAW 
Clue: In Latin legal lingo it means "by the fact itself"

SOLUTION: ipso facto

PROBLEM: Category: 20th CENTURY NICKNAMES 
Clue: Richard Nixon's aides Haldeman & Erlichman were sometimes called these comic-strip "Kids"

SOLUTION:
katzenjammer