Legal Definitions - just-war doctrine

The just-war doctrine is a set of principles, primarily in international law and ethics, that guides when it is morally and legally permissible for a nation to engage in war and how that war should be conducted. It essentially asks two main questions:

• Is it right to go to war? (known as jus ad bellum, or "justice in going to war")
• Is the war being fought in a right way? (known as jus in bello, or "justice in the conduct of war")

The doctrine asserts that a war must have a serious and justifiable reason (a "just cause"), meaning all peaceful alternatives have been exhausted and the war is a last resort to correct a grave wrong or prevent catastrophic harm. Furthermore, once a war begins, it must be conducted with restraint, using only the necessary force, distinguishing between combatants and non-combatants, and avoiding unnecessary suffering.

Here are some examples illustrating the just-war doctrine:

• Responding to a Cross-Border Invasion: Imagine "Nation A" launches an unprovoked military invasion into "Nation B," occupying its territory and targeting civilian infrastructure. After exhausting diplomatic efforts and appeals to international bodies, Nation B mobilizes its military to repel the invasion. During its counter-offensive, Nation B specifically targets military installations and combatants, taking measures to avoid civilian casualties and damage to cultural sites.

  Illustration: Nation B's decision to go to war would likely be considered a "just cause" because it is responding to an act of aggression and defending its sovereignty and population. Its conduct in the war, by targeting military objectives and minimizing civilian harm, demonstrates adherence to the principles of "just conduct" under the doctrine.

• International Intervention to Prevent Genocide: In a fictional country, "Xylos," the government begins systematically persecuting and exterminating a minority ethnic group. International observers confirm widespread atrocities and a clear intent to commit genocide. After the United Nations Security Council passes a resolution authorizing military intervention to protect the endangered population, a coalition of nations deploys forces. Their mission is strictly limited to stopping the genocide and protecting civilians, using precise military operations to neutralize the perpetrators without occupying the country long-term or engaging in broader regime change.

  Illustration: The intervention in Xylos could be argued as having a "just cause" due to the extreme humanitarian crisis and the international community's responsibility to prevent genocide. The coalition's commitment to a limited mission, focused on protecting civilians and avoiding unnecessary destruction, reflects the principles of "just conduct."

• A Nation's Response to State-Sponsored Terrorism: Following a series of devastating terrorist attacks orchestrated by a non-state actor operating from within "Nation C," which Nation C's government openly supports and harbors, "Nation D" launches targeted military strikes. Nation D's strikes are highly specific, aimed only at known terrorist training camps and command centers within Nation C, carefully avoiding civilian areas and infrastructure not directly linked to the terrorist operations. Nation D also publicly states its limited objective: to dismantle the terrorist network, not to overthrow Nation C's government or occupy its territory.

  Illustration: Nation D's decision to use force could be argued as a "just cause" if it can demonstrate that Nation C's active support for the terrorists constitutes an act of aggression or a grave threat, and all other diplomatic and economic pressures have failed. The precision and limited scope of Nation D's military actions, designed to minimize collateral damage and achieve a specific, defensive objective, exemplify the "just conduct" aspect of the doctrine.