The buddhist dillema on lesser evil Imagine this scenario: A serial killer is pointing his gun at an innocent person John and wants to kill John. An arahant is near the killer and knows that the killer will kill 5 more innocent people after he kills the innocent person John. The arahant can choose to kill the killer before the killer kills John and the other 5 innocent persons. Would the arahant kill the killer? Would a Buddha kill the killer? If yes, why? If no, why?
"Would the arahant kill the killer? Would a Buddha kill the killer?"


  'Yes, Sutavā, you heard correctly [...]. A bhikkhu who is an arahant [...] is incapable of transgression in nine cases. (1) He is incapable of intentionally depriving a living being of life"
  
  --  AN 9.7 (Bodhi trans.)





  "Here, Visakha, a noble disciple considers thus: 'For all their lives the arahants dwell having abandoned killing living beings, refrain from killing living beings, they have laid down their staffs, laid down their weapons, they are conscientious, sympathetic, compassionate for the good of all living beings; so today I dwell, for this night and day, having abandoned killing living beings, refraining from killing living beings, I am one who has laid down my staff, laid down my weapon, I am conscientious, sympathetic, compassionate for the good of all living beings. By this practice, following after the arahants, the Uposatha will be entered on by me.'"
  
  -- AN 8.43




"If no, why?"


  Through greed a covetous man kills breathing things [...]. Through hate a malevolent man kills breathing things[...]. Through ignorance a deluded man kills breathing things... Will that be long for his harm and suffering?" — "Yes, venerable sir."
  [...]
  Through non-greed an uncovetous man does not kill breathing things [...]. Through non ill-will an unmalevolent man does not kill breathing things. [...] Through non-delusion a man with true knowledge does not kill breathing things... Will that be long for his welfare and happiness?" — "Yes, venerable sir."
  -- AN 3.66


Summarizing, it's wrong action:


  And what is wrong action? Killing, taking what is not given, illicit sex. This is wrong action.
  
  -- MN 17