Respect for the rule of law at the national and international levels is the fundamental purpose of the UN. While the UN has several methods of enforcing international law, all of those methods require collective action. This has the advantage of establishing a collective response. On the other hand, the success of these methods depends on the willingness of the UN’s member nations to cooperate in deciding on a course of action and enforcing it.
Breaches of international law which threaten the peace
Enforcement of international law where the breach of law threatens the peace is governed by Chapter VII of the United Nations Charter. The UN Security Council is responsible for deciding appropriate enforcement measures. It is also responsible for determining the existence of any threat to the peace, breach of the peace, or act of aggression.
The Security Council’s effectiveness in this role is limited by the structure of the Security Council. Any of its permanent members may veto a decision without being required to account for its actions. This means that actions mandated by the Security Council are often limited in their severity.
By definition, the Security Council can never agree on any kind of international law enforcement against a permanent member of the Security Council, because that member will veto the action. The same goes for nation-states which have strong economic or political relations with a permanent member of the Security Council. This was originally intended to eliminate the chance of war among nuclear powers. However, it also means that the Security Council’s effectiveness in dealing with threats to peace is usually limited to marginal nation-states which do not have strong ties with any of the permanent Security Council members.
= Provisional measures =
To prevent escalation of the situation, the Security Council may set provisional measures and ask the parties involved to comply with them voluntarily. Provisional measures during active hostilities usually start with a request for a bilateral ceasefire.
These provisional measures are not intended as law enforcement. Instead, they may stabilize the situation until it can be assessed and a better solution can be found. Failure to comply with provisional measures will be taken into account when determining the subsequent course of action.
= Sanctions, communication, transportation, and diplomacy =
Under Article 41, the initial enforcement of law should consist of measures which do not involve armed force whenever possible and reasonable. These measures may include various levels of economic sanctions, discontinuation of transporation and communication links, and severance of diplomatic relations. The member states of the UN are expected to assist in applying these measures.
Joint economic sanctions are the most common type of enforcement used by the Security Council. Trade embargos may be selective or comprehensive. A selective embargo only targets trade in a few specified goods, such as materials with military applications. A comprehensive embargo completely severs all trade ties except for humanitarian items.
Economic sanctions take time for their effects to be noticeable. Their strongest effects may be on the general population. In many cases, policy-makers may be shielded from their effects.
The combination of these methods of enforcement was probably most effective in ending the apartheid regime of South Africa. Their effectiveness was directly related to the number of powerful nations which were willing to cooperate.
= Military intervention =
If these measures fail or are deemed inadequate, the Security Council has the power to call upon military intervention. The armed forces which participate in this military action are drawn voluntarily from various member states of the UN, according to their willingness to participate and contribute. Under Article 44, any member state which is contributing armed forces to a UN military mission has the right to participate in the decisions of the Security Council concerning how those forces are used.
Although the original Charter envisioned that every member state would have armed forces and facilities on standby for this purpose, this has never reached the level of formal agreement. Instead, the Security Council authorizes member states to cooperate while using the appropriate level of force against the target party or parties.
A range of military actions is available to the Security Council. At the low end are military demonstrations of force and blockades. Other, stronger military operations are also available, up to and including a full military invasion and armed intervention.
Because of the lack of a standing force, pulling together the necessary numbers of armed personnel can take a great deal of time. A fast-moving crisis may have already peaked and passed during this time, sometimes with great loss of life. This was the case during the Rwandan genocide.
After the initial military intervention, a peacekeeper force may remain in the area until peace is deemed to have been restored. This may be for just a few months, years, or even decades. Peacekeeping mlitary observers have been deployed in the Middle East since 1948, and in Kashimir since 1949. A full peacekeeping force has been deployed in Cyprus since 1964.
Enforcement of international law in other circumstances
Most treaties have enforcement provisions written into their text. The most common form of enforcement is an arbitration committee which has been set up by the treaty. UN treaties usually result in the creation of UN arbitration committees, although bilateral and multilateral treaties may also be concluded and enforced outside UN auspices.
Treaties may also be enforced through the International Court of Justice, the primary judicial organ of the UN. Referral to an ICJ ruling is most common when a provision for enforcement is not written into the treaty text.
Only UN member-states can apply for a ruling at the ICJ. Anyone else, such as minorities, organizations, indigenous peoples, or private enterprises cannot appeal to the ICJ.
In all cases, all the involved parties must agree to be bound by the ruling. Permanent members of the Security Council can veto the findings of the ICJ.
Tacit enforcement of international law
Most states abide by international law because they can expect reciprocity of their actions if they should breach the law. The Geneva Conventions on the Ethical Treatment of Prisoners arose out of this kind of reciprocity. Another common method of reciprocity is the use of tariffs, although this can easily spiral out of control into a trade war, which may require UN intervention to end.