Lawful Weapons

Demystifying legally restricted weapons in armed conflicts; a look into the means and methods of warfare.

The Prohibition of Superfluous Injury or Unnecessary Suffering

(This is the deciding factor in whether a weapon is prohibited under IHL.)

Article 35, paragraph 2 of Additional Protocol I prohibits parties to a conflict from employing weapons, projectiles, material, and other methods of warfare which are of a nature to cause superfluous injury of unnecessary suffering.

IHL restricts/ prohibits certain weapons which cause severe injury to soldiers and civilians, and at the same time are unnecessary to win the war.

Superfluous injury/ unnecessary suffering

There is no treaty-specified definition, however, states have generally agreed that a balance must be struck between military necessity and considerations of humanity.

The International Court of Justice affirmed in their "Nuclear Weapons Advisory Opinion" that is unlawful to cause harm to combatants which is greater than that unavoidable to acheive legitimate military objectives e.g. a ban on weapons with exploding/ expanding bullets, like dum dum bullets.

The Prohibition of Indiscriminate Attacks

(Attacks that cannot be directed at specific military objectives.)

Article 51, paragraph 4 of Additional Protocol I states that weapons which cannot be directed at specific military objectives and which consequently strike military objectives and civilians without distinction are indiscriminate and therefore prohibited.

Paragraph 5 further purports that this includes weapons expected to cause excessive collateral damage e.g. landmines triggered by combatants or civilians with no distinction.

Individual states have further implemented more specific weapons regulations as they see fit.

The use of conventional weapons in the conduct of hostilities is regulated specifically by the 1980 Convention on Certain Conventional Weapons and its 5 additional protocols (as well as scattered throughout various other conventions).

In consequence to weapons of mass destructions' detrimental nature, states have prohibited the use of chemical and biological weapons in separate conventions:

• The Chemical Weapons Convention

• The Biological Weapons Convention

"Conflicting parties shall never under any circumstances make use of these weapons in the conduct of hostilities. The prohibition is absolute"

Nuclear Weapons

Nuclear weapons have not been explicitly banned, however technically would be indirectly banned according to the above principles.

In July 2017, the Treaty on the Prohibition of Nuclear Weapons was signed, but it is not currently enforced nor legally binding.

Article 36 of Additional Protocol I obliges state parties to conduct legal reviews on new weapons. Autonomous weapons and drones are not banned yet, and there is much debate surrounding this within the realm of IHL.