Ok. I have watched agll three OT movies the last two days, so I have gall these things running through my mind.
Luke, calling himself a Jedi Knight in ROTJ, knowing what he learned from Yoda, tells Jabba "Free us or Die".
Yoda told Luke, a Jedi's weapon is his lightsaber. It is used for defense, not murder(attacking). Luke knew fully that Jedi were peace keepers. He pretty much planned the whole rescue of Han from Jabba's Palace. He had to know that the plan might end up in violence. So, he pre-meditated murder, a trait of the Dark Side. Luke started down that pgath in ROTJ with this, and he came really, regally close at the end of the movie. The only difference was he was able to stop short of Killing his Dad.
Anakin also pre-meditated murder when he killed the Tuskens after his Mom Died. It wasnt like he was trying to get away and had to fight his way out, he basically went out there and slaughtered them. he says so(in a horrible acting scene).
So, basically what I am saying is Yoda also said, once you start on the path of the Dark Side, you can not turn back. Luke started going down the path, does he turn back? or does he keep going. I know in EU he goes to the dark side and returns again, but what do you think of this mentally unstable boy we have grown to love called Luke Skywalker?