The Just War Theory also known as the Jus ad Bellum is a dubious theory on the basis of which, through the ages, nations have sought to legally and morally justify the taking up of arms. The foundation for the Just War Theory was laid by Augustine in the 4th century. About eight centuries later, during the high middle ages, Augustine’s reflections were codified into the distinct criteria by Thomas Aquinas. These criteria remain the basis of the Just War Theory as it is known today. They are:
- Just Authority: Also known as Competent Authority, Just Authority states that a just war must be initiated by a political authority within a political system that allows distinctions of justice.
- Just Cause: In order to produce a justification, an authority must be able to show that some wrong has been committed by one nation for which war is thought to be the proper response.
“I strongly believe that there is a Christian doctrine of just war.”
– Ron Paul
- Just Intention: A warring state is prevented from going beyond the boundaries of its justification by acting according to its justified intentions.
- Last Resort: War is morally permissible only when there is no other course of action open. This means that the nation considering war has exhausted all potential solutions, including political and diplomatic.
– Courtesy of oregonstate.edu
“Violence and arms can never resolve the problems of men.”
– Pope John Paul II
Knowledge Guild 
History does show that there are some just wars among the vast numbers of unjust ones. Resisting power-motivated aggression is surely reasonable motivation, where the alternative is to submit tamely to a despised regime.