Why are poison and poisoned weapons prohibited under the Hague Convention of 1907?

The prohibition of poison and poisoned weapons under the Hague Convention of 1907 is rooted in the fundamental principle that the right of belligerents to adopt means of injuring the enemy is not unlimited.1

This restriction is based on the ethical standard established by the 1868 Declaration of St. Petersburg, which asserts that the only legitimate objective of states during war is to weaken the military forces of the enemy. Consequently, international law prohibits weapons or materials that are calculated to cause unnecessary suffering. By banning the use of poison, the convention seeks to uphold the principle of humanity in warfare, ensuring that combatants are not subjected to methods of injury that exceed what is necessary to achieve a legitimate military goal.12