There are two components in the concept of a “just war”.  One being the justifications required that lead to a declaration of war, and the second, concerning how the parties involved in a war conduct themselves in the conflict.

Several early scholars and philosophers attempted to justify the use of armed force under certain conditions.  Cicero, in the 1st century BCE, wrote that a war can be legitimate if openly declared, has a just cause, and is conducted in an ethical manner.  Christian leaders, such as St. Augustine in the 5th century, felt that war can be rationalized based on theological principles.  Around the mid-point of the Middle Ages (500 – 1500) religious and secular elements blended together to produce a more coherent body of thought about declaring and conducting a just war.  At the same time, the chivalric code became an important element in the consideration of noncombatant immunity and other restraints during a conflict.

By the time colonization was fully underway in the 16th and 17th centuries, war could be declared and considered ‘just’ if it met these conditions:

    1. Declared openly by a proper sovereign and governing authority;
    2. Had a ‘just’ cause, such as in defense of the common good or in response to a grave injustice;
    3. Was a war for justice rather than for self-interest;
    4. The aim of the war was to establish a ‘just’ peace;
    5. There was a reasonable chance of success;
    6. War was used only as the last resort; and
    7. The benefits outweigh the anticipated costs.

After the Thirty Years’ War ended in the mid 1600s, there was a more concerted attempt to create a binding set of international laws of war and military codes of conduct.  These efforts eventually resulted in the Geneva and Hague Conventions and other standards, codes, agreements and treaties governing conduct during a war.  Generally, there are three principles that set the rules for military engagement during a war:

    1. Targets should include only combatants and legitimate military and industrial complexes;
    2. Combatants should not use ‘unjust’ methods or weapons (e.g., torture, genocide); and
    3. The force used should be proportionate to the end sought.

Primary Source: James T. Johnson, Rutgers University; Encyclopedia Britannica, February, 2005

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