I found the article in the post above linked in this article:
http://massively.joystiq.com/2014/01/17/...-pvp/#continued

I didn't play SWG at all. After reading this article I assume that there was a PVP flag that you could toggle on/off. If you're a republic player that attacks a imperial NPC during a quest, you get flagged for PVP for 10-15 minutes.

The problem with a system like this is that it's more of a RESTRICTION than a rule. People can choose to leave their PVP flag off and I am RESTRICTED from attacking them.

I think a better way (not perfect) is the whole blue/red system where everyone is blue until they kill enough people to become grey. If you commit a "red" action, you become "grey" for 10-15 minutes which means blues can kill you without consequence. This has it's flaws of course but is still better than a PVP on/off toggle that is more of a restriction than a rule.

One idea to counteract the whole blue jumps in front of another blue while fighting to turn him grey would be to have the first hit from a blue vs. another blue not turn him "grey". I'm sure it would be abused by having 10 guys hit the same guy all at once to kill him, but someone is going to get the kill shot and take an alignment hit for it. You could also put in place a system like Mortal Online had that once you are killed, anyone that did damage to you in the last few minutes you are given the option to assign an alignment hit to them as well. This of course can be exploited also by blue naked people who will jump in front of you, take damage, suicide, then assign an alignment penalty to you.

No real solid answer to an alignment system in a game with FPS style aiming at least. Tab target would be pretty easy.