The possibility of withdrawal depends on the terms of the contract and its preparatory work. For example, it was found that it was not possible to withdraw from the International Covenant on Civil and Political Rights. When North Korea announced its intention to do so, the UN Secretary-General, as registrar, said that the original signatories to the ICCPR had not neglected the possibility of explicitly withdrawing, but deliberately intended not to provide for it. Therefore, it was not possible to withdraw.  Originally, international law did not accept and rejected the terms of the treaty, unless all parties accepted the same reservations. However, in order to encourage as many States as possible to accede to treaties, more permissing regulations on reservations had emerged. While some treaties still expressly prohibit reservations, they are now generally permitted to the extent that they are not contrary to the objectives and purposes of the treaty. If a party has breached or materially breached its contractual obligations, the other parties may invoke that breach as a ground for the temporary suspension of its obligations to that party. A substantial infringement may also be invoked as a ground for permanent termination of the contract itself.
 Flare Index to Treaties (Open Access on the website of the Institute of Advanced Legal Studies (IALS)) – a searchable database containing basic information on more than 2,000 of the major multilateral treaties and some bilateral treaties concluded between 1353 and today, with details of where the full text of each contract is available on paper and, where applicable, Electronic form on the Internet. Unless a contract contains provisions concerning other agreements or acts, only the text of the treaty is legally binding. Generally speaking, a treaty amendment is binding only on States that have ratified the amendment and agreements reached at review conferences, summits or meetings of States parties are political, but not legally binding. The Charter of the United Nations is an example of a treaty that contains provisions relating to other binding agreements. By signing and ratifying the Charter, countries have agreed to be legally bound by resolutions adopted by UN bodies such as the General Assembly and the Security Council. Therefore, UN resolutions are legally binding on UN Member States and no signature or ratification is required. In terms of function and efficiency, the UN has been compared by some to the pre-constitutional federal government of the United States, indicating a comparison between modern contract law and the historical articles of Confederation. World Treaty Index (Open Access) – contains metadata for nearly 75,000 contracts that came into effect in the twentieth century. Users can search for many access points, including citation; keyword of the title; the name of the party (including countries and organizations); subject; whether the treaty is bilateral or multilateral; and the date of signature. A contract is void and not abnormal if it is contrary to a peremptory norm. Unlike other principles of customary law, these norms are recognized as inadmissible and therefore cannot be modified by contractual obligations. These are limited to universally recognized prohibitions, such as the fight against the aggressive use of force, genocide and other crimes against humanity, piracy, hostilities against the civilian population, racial discrimination and apartheid, slavery and torture, which means that no state can legally assume an obligation to commit or authorize such acts.
 The separation between the two is often unclear and often results in differences of opinion within a government about a treaty, since a non-self-executive treaty cannot be implemented without a proper amendment of domestic law. If a treaty requires implementing laws, a State cannot fulfil its obligations by failing to adopt the necessary national laws by its legislator. . . .