States are sovereign; they determine their own laws and regulate their own actions. Interactions between states are therefore always to some extent a matter of realpolitik. Nevertheless there is a collegial system of law based on treaties, decisions by the United Nations along with whatever enforcement the members of that body agree on a case by case basis, and a sort of common law derived from legal principles agreed as a sort of international concensus.
The International Court of Justice was established in 1946 as a part of the UN to aid in dispute resolution. Security Council members appoint judges, as do other countries on a rotating basis. Most countries, with the notable exception of the United States, agree to be bound by ICJ decisions. There are a number of important treaties from the Law of the Sea to the Nuclear Non-Proliferation Treaty. In addition there are various conventions and traditions which govern the operation of countries in the international arena.
So there are mechanisms to determine what constitutes legal and illegal behaviour by a state. Enforcement, on the other hand, is a far more arbitrary matter. This depends upon what sanctions are agreed by the United Nations or other international bodies, and what can be enforced by threat or direct action by the international community.
The situation with Iran and nuclear weapons is a good example. Iran signed the Nuclear Non Proliferation Treaty (NPT). Under the treaty it is allowed peaceful use of nuclear technology, for example to generate power, but it is obliged to allow inspection. It is not allowed to develop or acquire nuclear weapons. The US has referred it to the UN for sanctions because it believes it is in breach of this requirement. As a nuclear state and signatory to the NPT, the US is by the way obliged to take steps toward disarmament – something it has only undertaken in a half-hearted way. It has from time to time reduced its total arsenal, but it has continued to develop new weapons and it has explored new and directly illegal types of weapons, such as low yield and battlefield weapons. As a powerful state with many allies the US is unlikely to be brought to account for this any time soon.
There are two norms which have a long history and are permanently established in treaty since 1977 as part of the Geneva conventions. The ICJ has determined that these two norms have general application, a status equivalent to common law, and therefore bind even states not signatory to the Geneva conventions or the ICJ. They are the principle of discrimination and the principle of proportionality.
I’ll quote some pieces of the Geneva convention, as it’s not at all unclear, but skip past the quoted material if you want the “executive summary”:
- Part IV. Civilian Population
- Section I. General Protection Against Effects of Hostilities
- Chapter I. Basic rule and field of application
- Art 48. Basic rule
- In order to ensure respect for and protection of the civilian population and civilian objects, the Parties to the conflict shall at all times distinguish between the civilian population and combatants and between civilian objects and military objectives and accordingly shall direct their operations only against military objectives.
- Art 49. Definition of attacks and scope of application
- “Attacks” means acts of violence against the adversary, whether in offence or in defence.
- Chapter II. Civilians and civilian population
- Art 50. Definition of civilians and civilian population
- A civilian is any person who does not belong to one of the categories of persons referred to in Article 4 (A) (1), (2), (3) and (6) of the Third Convention and in Article 43 of this Protocol. In case of doubt whether a person is a civilian, that person shall be considered to be a civilian.
- The civilian population comprises all persons who are civilians.
- The presence within the civilian population of individuals who do not come within the definition of civilians does not deprive the population of its civilian character.
- Art 51. – Protection of the civilian population
- The civilian population and individual civilians shall enjoy general protection against dangers arising from military operations. To give effect to this protection, the following rules, which are additional to other applicable rules of international law, shall be observed in all circumstances.
- The civilian population as such, as well as individual civilians, shall not be the object of attack. Acts or threats of violence the primary purpose of which is to spread terror among the civilian population are prohibited.
- Civilians shall enjoy the protection afforded by this section, unless and for such time as they take a direct part in hostilities.
- Indiscriminate attacks are prohibited. Indiscriminate attacks are:
- those which are not directed at a specific military objective;
- those which employ a method or means of combat which cannot be directed at a specific military objective; or
- those which employ a method or means of combat the effects of which cannot be limited as required by this Protocol;
and consequently, in each such case, are of a nature to strike military objectives and civilians or civilian objects without distinction.
- Among others, the following types of attacks are to be considered as indiscriminate:
- an attack by bombardment by any methods or means which treats as a single military objective a number of clearly separated and distinct military objectives located in a city, town, village or other area containing a similar concentration of civilians or civilian objects; and
- an attack which may be expected to cause incidental loss of civilian life, injury to civilians, damage to civilian objects, or a combination thereof, which would be excessive in relation to the concrete and direct military advantage anticipated.
- Attacks against the civilian population or civilians by way of reprisals are prohibited.
- The presence or movements of the civilian population or individual civilians shall not be used to render certain points or areas immune from military operations, in particular in attempts to shield military objectives from attacks or to shield, favour or impede military operations. The Parties to the conflict shall not direct the movement of the civilian population or individual civilians in order to attempt to shield military objectives from attacks or to shield military operations.
- Any violation of these prohibitions shall not release the Parties to the conflict from their legal obligations with respect to the civilian population and civilians, including the obligation to take the precautionary measures provided for in Article 57.
- Art 54. Protection of objects indispensable to the survival of the civilian population
- Starvation of civilians as a method of warfare is prohibited.
- It is prohibited to attack, destroy, remove or render useless objects indispensable to the survival of the civilian population, such as food-stuffs, agricultural areas for the production of food-stuffs, crops, livestock, drinking water installations and supplies and irrigation works, for the specific purpose of denying them for their sustenance value to the civilian population or to the adverse Party, whatever the motive, whether in order to starve out civilians, to cause them to move away, or for any other motive.
- Art 57. Precautions in attack
- In the conduct of military operations, constant care shall be taken to spare the civilian population, civilians and civilian objects.
- With respect to attacks, the following precautions shall be taken:
- (a) those who plan or decide upon an attack shall:
- (iii) refrain from deciding to launch any attack which may be expected to cause incidental loss of civilian life, injury to civilians, damage to civilian objects, or a combination thereof, which would be excessive in relation to the concrete and direct military advantage anticipated;
What does it all mean? The short version can be listed as follows:
- The principle of distinction: attacks may not be directed against civilian objectives. If there is the potential for civilian casualties (collateral damage) then –
- The principle of proportionality: applies. This means that the military advantage must be significant compared to the level of civilian casualties.
But there are some interesting additional requirements here:
- It’s still a civilian population even if it contains some non-civilian individuals.
- Using civilians as a shield is illegal – but a breach by one party explicitly does not absolve the other party from the requirements of this convention
- Bombardment of military objectives in a populated area is prohibited.
- Starvation of a civilian population and destruction of installations essential to their survival is prohibited.
I’m not going to draw examples from current world events into this – that’s easy enough to do. The point is, however, that it’s irrelevant so long as no sanctions can be levied, and an ally with a veto on the Security Council is a ticket to flout the law.