There are dozens of multilateral treaties and conventions. But in a Model UN context, some show up time and time again.
The Geneva Conventions are a group of four treaties and three protocols concerning humanitarian law and the treatment of people during wartime. The four Conventions were created in 1949, updating the two Geneva Conventions of 1929. The three Protocols were added in 1977 and 2005. The Conventions cover the treatment of the sick and wounded during armed conflicts, the treatment of prisoners of war, and the treatment of civilians.
The International Covenant on Civil and Political Rights (ICCPR) and the International Covenant on Economic, Social and Cultural Rights (ICESCR) establish legal obligations for the upholding of human rights. They mirror the language of the Universal Declaration of Human Rights. Each has an optional protocol that establishes a quasi-judicial review process. There are a number of other human rights treaties that establish additional obligations in specific areas: the Convention Against Torture (CAT), the Convention on the Elimination of All Forms of Racial Discrimination (CERD), the Convention on the Elimination of All Forms of Discrimination Against Women (CEDAW), the Convention on the Rights of the Child (CRC or CROC), and the Convention on the Rights of Persons with Disabilities (CRPD).
The UN Convention on the Law of the Sea (UNCLOS) describes the obligations of States concerning the world’s oceans. Most importantly, it provides for some environmental stewardship and establishes the terms for economic use of marine resources, including mineral resources. Disputes under UNCLOS are some of the most common international legal conflicts today.
The United Nations Framework Convention on Climate Change (UNFCCC) and the Kyoto Protocol establish State obligations and responsibilities to address climate change. The UNFCCC establishes no obligations itself. Instead, it establishes a process through which protocols with targets and obligations can be negotiated by States. The Kyoto Protocol established national targets for greenhouse gas emissions. The Paris Agreement was also established under the UNFCCC.
The Vienna Convention on Diplomatic Protocols establishes how States are to treat the diplomatic representatives of other States, including principles such as diplomatic immunity. It also established the principle that diplomats should not be harassed, intimidated or coerced. Note that there are several other Vienna Conventions, as well, including the Vienna Convention on Consular Protocols and the Vienna Convention on the Law of Treaties.
The Biological Weapons Convention, Chemical Weapons Convention, and the Treaty on the Non-Proliferation of Nuclear Weapons establish limitations on the stockpiling and use of certain weapons of mass destruction.
Last but not least, the United Nations Charter is itself a treaty, as are the constitutions of many UN technical organizations. The Charter is, in many ways, the most foundational of them all. It establishes much of the modern international system that we simulate in Model UN. It also provides us with the ambitious goal that drives much international law: “to establish conditions under which justice and respect for the obligations arising from treaties and other sources of international law can be maintained.”