SilverWook said:Not every director enjoys as much control as Lucas does, and movie scripts are often rewritten by many others whose names never appear on the final product.
Some of the better dialog between Indy and Marion in Crystal Skull has been attributed to Kasdan.
That last bit would not surprise me in the slightest. Some of their retorts were the freshest dialogue in that mess.
Kershner even talks about what he tried to do on Never Say Never Again and all the troubles he ran into because of the control issue.