Found on the internet:
"It is interesting that Liel raises the “Han shot first” ruckus without mentioning that al pi Halakha what Han did was absolutely moral. Greedo came to collect a debt. Han, a shomer sakhar in Jabba’s employ, was forced to jetison the cargo he was delivering for Jabba. Han insists to Greedo that he doesn’t have the cash to pay Jabba the debt, but will soon (once he gets back from ferrying the old man, boy and two droids to Alderaan). Greedo instead insists that he has the right to seize Han’s ship. When Han refuses (“Over my dead body!”) Greedo threatens to kill Han. At this point Greedo is a rodef, and even if he hasn’t pulled the trigger on his blaster pistol, the fact that he IS pointing one at Han, entitles Han to kill Greedo to save his life. But that is not good enough for the Lucas of 1997. :( "