While disarming our planet in today’s world includes among other things the goal of eliminating the use of weapons of mass destruction in large- and small-scale combat situations we generally describe as war, one wonders when and how did the notion of “war” and a soldier’s “right to kill” ever originate.

Authors Oona A. Hathaway and Scott J. Shapiro take up this question in their book called The Internationalists. They begin with reference to a meeting in Paris in 1928, following the end of World War I. The gathering was for “The Signing of the General Pact for the Renunciation of War,” better known as the Paris Peace Pact or, in the U.S., the Kellogg-Briand Pact (p. ix). While the Pact essentially failed to prevent war, as the subsequent events of the 1900s clearly show, it did reveal a change in thinking, a change which continues to this day as we consider the use of artificial intelligence and cyber methodologies. What has not changed is the acknowledgment of a soldier’s right to kill.

Where did that come from? These authors propose an answer: Hugo Grotius, whom history buffs may recall learning about as the “father of international law.” Grotius was a Dutch lawyer and philosopher of the 16th century, “the most creative and articulate exponent of the idea that states are permitted to wage war against each other in order to enforce their legal rights” (p. xix). This was to be the Old World Order. He endorsed war as being “good for many things… [like] defending lives and territory,” but also for collecting debts on unpaid loans, or for restitution (property taken without permission), or collecting reparations, or punishing criminals (p. 9). This came to be known as “just war theory”: A war is said to be “just” if it consists in the execution of a right.

Grotius supported a “Might is Right” principle which states that “success creates legal rights in war” (p. 23). He saw morality in war and argued that the “law of nature permits individuals and states to use force to prosecute their rights” (ibid). Within this system, there was no way to legally distinguish between “just” and “unjust” wars. “In the Old World Order… abuse was not only possible – it was inevitable. But in the absence of global courts, if war is legal, Might must be Right, even if it is wrong” (p. 55).

This kind of thinking then led to a license to kill, especially for the soldier fighting on either side in a declared war. This license was an ancient right, according to Grotius and his ilk. As established, “self-defense was not the only just cause of war. Soldiers had the legal right to kill … to satisfy debts, collect damage awards, enforce hereditary rights of their monarch, or punish wife stealing” (p. 62). Soldiers enjoyed an absolute immunity from prosecution even if their side was waging an unjust war. We could see this thinking applied to German soldiers (not necessarily officers) after World War II.

How much of this thinking has changed? While the current laws of war endorse the Geneva Conventions (revised in 1949 after WWII) which imposed constraints on the waging of war (e.g. protection of civilians, respecting the surrender of the enemy and the rights of a war prisoner), it has expanded in outlawing rape, sexual slavery, enforced prostitution or other sexual violence, intentional starvation, conscripting children or use of prohibited weapons (Kalshoven & Zegvels: Ch. 2).

The authors of The Internationalists note the strangeness of the rules of the Old World Order where criminal activities became essentially legal once a war was declared. “Soldiers did not merely have the license to kill in war. They also had the license to trespass, break and enter, steal, assault, maim, kidnap, extort, destroy property, and commit arson – … actions that would be crimes if committed in peacetime” (p. 63). Grotius did, however, recognize war crimes such as the use of poison, treacherous assassination, and rape (p. 71). These actions caused a soldier to lose his license to kill.

So what has changed with the New World Order brought about by the creation of the United Nations and the notion of global cooperation? Essentially the rules of war identified by Grotius have been reversed with a focus on a “prohibition on force”. Concepts such as “conquest is illegal, aggression is a crime, no coerced agreements, and sanctions are permitted” now prevail as consequences of the prohibition on force (p. 304).

In reading the Rome Statute, which created the International Criminal Court, one can readily see that individuals can be held responsible for committing acts of genocide, war crimes, crimes against humanity, and ethnic cleansing. Over 120 countries have ratified this Court and individuals are tried and indicted by the ICC when accused of war crimes or crimes against humanity.

The conduct of war and the license to kill have been changing. Supporters of disarmament live with the hope that in their lifetimes, war will become passé. At least efforts continue to humanize it.

Page numbers cited are from:

Hathaway, Oona A., and Scott Shapiro. The Internationalists: How a Radical Plan to Outlaw War Remade the World. Simon & Schuster, 2017.

Also cited:

“Chapter 2.” Constraints on the Waging of War, by Frits Kalshoven and Liesbeth Zegvels, 4th ed., Cambridge University Press, 2011, pp. 8–29.