For all the people arguing about the Anti Team Kill addon; let me give a brief explanation of what it does.
If a detectives shoots a detective by mistake, it will not affect the victim's health but it will only affect the attacker's karma.
If a traitor harms his traitor buddy in anyway, it will not affect the victim's health in anyway; not even C4s or Jihads or anything.
So, I don't see why this is so bad.
These settings are completely configurable.