I seem to remember reading about it in Robert Heinlein`s Take Back Your Government, written in 1947, but published posthumously in 1992.
There`s an entry on it in Safire`s Political Dictionary, where Safire discusses a 1966 incident in which Frank O`Connor, Jacob Javits`s opponent, threatened to pull the "empty chair" trick on Javits, who was wrangling over debate terms. Javits`s representative
"shook his head. “That’s against FCC regulations,” he said with a straight face. “This is a four-man race. You’d have to debate three empty chairs.”
Since most of the people complaining about it are leftwing progressive types at the Daily Kos, here`s one classic use of it: