SilverWook said:

IIRC, the Director's Guild, (which George had conflicts with and quit of course) has very specific criteria, as the issue of who really directed a film has come up on other productions.

You can make the argument that Lucas co-directed Jedi, but not Empire.

Who cares about DGA. Under their criteria being a co-director isn't even possible. Definition of "director" can vary anyway. What I was trying to say was that Lucas was (overall) the principal author of both Empire and Jedi.