For my part when it comes to NPC's it goes:<br/><br/>Martian Manhunter - Doesn't kill and will not tolerate killing, torturing or any other similar immoral act.<br/><br/>Doctor Fate - Doesn't kill but can tolerate others killing in extreme situations.<br/><br/>The Flash - Doesn't kill and isn't going to tolerate others who do/would.<br/><br/><hr/><br/>I don't know if the JL typically have a clear cut set of rules but I would say no killing is a requirement of members at this point, since so many will not tolerate it and it's fitting with the team.