Ok here is the problem.
Feat1) Sacred VOw. You are seen as an almighty good person by all the other good people.
Feat 2) Vow of Nonviolence. You get bonuses to spell DC's that don't do damage. The price is that you may never deal lethal damage again! If your allies slay a helpless or defensless creature within 120 feet of you they take a -1 to all attacks for a number of hours equal to your level. This -1 can keep stacking up to the caster level and each time a new slaying occurs, the time starts over.
Rogue Ability: SNEAK ATTACK! OK, the book says "If a rogue can catch an opponent when he is unable to defend himself effectively from her attack, she can strike a vital spot for extra damage..."
The person who took the vow is not the person who is the rogue. The person who took it was entirely in charecter when they took the feat and I will not penalize that because that person had been acting that way almost all game and it only made sense for them to take it.
Now, I as a DM saw this Sneak attack to be included in the Defensless trait and only if he killed them would he get the negative.
Do you all agree with me that a rogues sneak attack is considered to be attacking a defensless person? This person also uses feinting to remove the persons DEx. I think this adds to my point of defensless, let me know what you think.