One of the challenges of the international legal system is that of enforcement. While the municipal legal system has developed mechanisms for law enforcement, including the police forces, the courts and prison systems, there is no equivalent in international law. That international law does not possess the same enforcement mechanisms as exist in municipal law is highlighted as a major point of distinction between the two legal systems. It is often said that in the absence of an ‘international policeman’ it is not possible to effectively enforce international law.
Enforcement mechanisms that have been developed since the creation of the United Nations (UN) in 1945 have transformed the international legal system from the one that pre-dated the outbreak of World War II. Principal among these has been the establishment of the International Court of Justice (ICJ) as the judicial organ of the UN – it has the capacity to resolve international legal disputes and deliver judgments that are binding upon those parties to the case, and that may ultimately be subject to Security Council recommendations if a party ‘fails to perform the obligations incumbent upon it’. In addition, the Security Council has significant powers under Chapter VII of the UN Charter to seek to ‘maintain and restore international peace and security’ and as part of that mandate the Council regularly adopts resolutions that are binding upon member States of the organisation and enforceable by way of various mechanisms, including economic sanctions. However, the capacity of the Security Council to sometimes act decisively in these matters has historically been hampered by the use of the veto by one of the Permanent Members (China, France, Russian Federation, United Kingdom, United States of America). This was particularly an issue during the Cold War, and while the veto is now not used as frequently it can have an impact on how the Security Council can respond to an international crisis involving violations of international law, as occurred with the Council's response to the events in Syria from 2011 onwards.
In addition to the UN Charter, since 1945 multilateral treaties have developed increasingly sophisticated mechanisms for enforcement.