LONDON NUCLEAR WARFARE TRIBUNAL
Evidence, Commentary, and Judgment

The lack of specificity in the Just War Doctrine was a shortcoming, as was the absence of any ritual of assent by which a sovereign authority acknowledged its duty to be bound in definite ways. International jurists collected the body of practices that governments accepted as binding upon themselves, and set forth these rules and principles beneath the label of customary international law. These rules and principles helped shape the direction of treaty law, and, as well, provided legally accepted yardsticks for measuring claims about the status of new weapons and tactics. Such rules and principles provide a normative background against which to evaluate the controversy about the lawfulness of nuclear weapons and about various doctrines governing their use.

• Principle of Discrimination - to be lawful, weapons and tactics must discriminate clearly between military and non-military targets, and be confined in their application to military targets. Indiscriminate warfare is per se illegal, although indirect damage to civilians and civilian targets is not necessarily so.
• Principle of Proportionality - to be lawful, weapons and tactics must be proportional to their military objective. Disproportionate weaponry and tactics are excessive, and as such, illegal.
• Principal of Lawfulness - to be lawful, weapons and tactics must not violate any treaty rule of international law binding as between the parties.
• Principle of Necessity - to be lawful, weapons and tactics involving the use of force must be reasonably necessary to the attainment of their military objective. No superfluous or excessive application of force is lawful, even if the damage done is confined to the environment.
• Principle of Humanity - to be lawful, no weapon or tactic can be relied upon that causes unnecessary suffering to its victims, whether by way of prolonged or painful death, or in a form that is calculated to cause severe terror or fright. For this reason, weapons and tactics that spread poison, disease, or do genetic damage are generally illegal per se, as being weapons with effects not confined in the place and time of damage to the battlefield. Such a prohibition, under contemporary circumstances, extends to ecological disruption in any form.
• Principle of Neutrality - to be lawful, no weapon or tactic can be relied upon that seems likely to do harm to human beings, property, or the natural environment in neutral countries. A country is neutral if its government declares itself to be so and if it pursues a policy of impartiality in relation to armed conflict, including the avoidance of any kind of alliance relationship.