here is the IMDB info on this subject... (of course the IMDB can be edited by unauthorized persons but its still there and not redacted so take with a grain of salt.. but may very well be true)
George Lucas asked
Lawrence Kasdan to write the script (and possibly for
Star Wars: Episode II - Attack of the Clones (2002) and
Star Wars: Episode III - Revenge of the Sith(2005) as well), but he turned it down because he thought with
Star Wars: Episode V - The Empire Strikes Back (1980) and
Star Wars: Episode VI - Return of the Jedi (1983), Lucas's relationship to the movies had taken one step back and that he alone should take responsibility and make exactly the movie he wanted to make.
George Lucas approached
David Hare to write the screenplay and even co-direct the film. Lucas confessed he had reservations about working with the actors, and hoped that he could focus on the action while Hare focused on the acting. Hare declined.
Frank Darabont was originally slated to be writing the script at one point, as was
Carrie Fisher, who was said to be helping out as a script doctor.
