Legal Definitions - justifiable war

A "justifiable war," also known by its Latin term bellum justum, refers to a conflict that is considered legitimate and morally permissible under international law and ethical principles. For a war to be deemed justifiable, it must meet certain strict criteria. These typically include having a legitimate reason for engaging in hostilities (such as self-defense against aggression or preventing widespread atrocities), being declared by a proper authority, and being undertaken only as a last resort after all peaceful means have been exhausted. The intent must be to restore peace and justice, not to gain territory or exact revenge.

Here are some examples illustrating the concept of a justifiable war:

• Self-Defense Against Invasion: Imagine a scenario where Nation X launches an unprovoked, large-scale military invasion into the sovereign territory of Nation Y, occupying its cities and attacking its civilian infrastructure.

  This would be considered a justifiable war for Nation Y because it is acting in direct self-defense against an act of aggression. International law recognizes a state's inherent right to defend itself from attack, making its military response legitimate and justifiable.

• Humanitarian Intervention Sanctioned by International Body: Consider a situation where a rogue regime within Country A begins systematically persecuting and massacring a large ethnic minority group, leading to a severe humanitarian crisis. After all diplomatic efforts, sanctions, and warnings fail, the United Nations Security Council passes a resolution authorizing a multinational force to intervene militarily to protect the civilian population and stop the atrocities.

  This intervention could be seen as a justifiable war because it is undertaken with a legitimate cause (preventing mass atrocities and genocide), is sanctioned by a recognized international authority, and is a last resort after peaceful means have been exhausted. The intent is to protect human life and restore stability, not for territorial gain.

• Collective Self-Defense within an Alliance: Suppose State B, a member of a defensive military alliance, is suddenly attacked and its borders are breached by a powerful neighboring State C. Under the terms of their alliance treaty, other member states, State D and State E, deploy their armed forces to assist State B in repelling the invasion.

  The military actions of State D and State E would be considered a justifiable war because they are acting in collective self-defense, coming to the aid of an ally that has been subjected to an unprovoked attack. This aligns with the principle of legitimate self-defense, extended to allies under mutual defense agreements.