By prosecuting and convicting war criminals, the UN tribunals established for the former Yugoslavia and for Rwanda have helped to expand international humanitarian and international criminal law dealing with genocide and other violations of international law. Both tribunals have contributed to restoring peace and justice in the affected countries and in the region. The International Criminal Court is an independent, permanent court that investigates and prosecutes persons accused of the most serious international crimes—genocide, crimes against humanity and war crimes—if national authorities are unwilling or unable to do so. Situations in the Democratic Republic of the Congo, northern Uganda, Sudan's Darfur region and the Central African Republic have been referred to the Court, which has already established itself as the centrepiece of the system of international criminal justice. UN-backed courts in Sierra Leone and Cambodia are prosecuting those responsible for serious violations of international law, including mass killings and war crimes.

Over 510 multilateral treaties—on human rights, terrorism, global crime, refugees, disarmament, trade, commodities, the oceans and many other matters—have been negotiated and concluded through the efforts of the United Nations.

By delivering judgments and advisory opinions, the International Court of Justice (ICJ) has helped to settle international disputes involving territorial questions, maritime boundaries, diplomatic relations, State responsibility, the treatment of aliens and the use of force, among others.

The United Nations has spearheaded international efforts to regulate the use of the oceans under a single treaty. The 1982 UN Convention on the Law of the Sea, which has gained nearly universal acceptance, provides the legal framework for all activities in the oceans and seas. The Convention lays down rules for the establishment of maritime zones, the rights and duties of coastal and landlocked States, including with regard to navigation, the protection of the marine environment, marine scientific research, and the conservation and sustainable use of marine living resources. The treaty includes mechanisms for settling disputes.

The UN Office on Drugs and Crime (UNODC) works with countries and organizations to counter transnational organized crime by providing legal and technical assistance to fight corruption, money-laundering, drug trafficking and smuggling of migrants, as well as by strengthening criminal justice systems. It helps countries to prevent terrorism, it is a leader in the global fight against trafficking in persons and, together with the World Bank, it helps countries to recover assets stolen by corrupt leaders. It has played a key role in brokering and implementing relevant international Treaties, such as the UN Convention against Corruption and the UN Convention against Transnational Organized Crime.

The UN Office on Drugs and Crime (UNODC) works to reduce the supply of and demand for illicit drugs under the three main UN conventions on drug control. The Office works with countries to improve public health, as well as public security, in order to prevent, treat and control drug abuse. Efforts to contain the global drug problem have reversed a 25-year rise in drug abuse and headed off a pandemic. Nevertheless, several countries and regions remain vulnerable to the instability caused by drug cultivation and trafficking. That is why the Office is particularly engaged in drug control in Afghanistan, the Andean countries, Central Asia, Myanmar and West Africa.

The World Intellectual Property Organization (WIPO) promotes the protection of intellectual property rights and ensures that all countries are in a position to harness the benefits of an effective intellectual property system. Intellectual property, which at its core is a mechanism designed to recognize and reward inventors and creators for their ingenuity while safeguarding the public interest, helps to promote development and create wealth. The incentives built into the intellectual property system act as a spur to human creativity, pushing forward the boundaries of science and technology and enriching the world of literature and the arts.