The obligation to adopt national implementation measures
Mexico and Saint Kitts and Nevis are examples of states parties that in 2022 reported that they intend to or are in the process of adopting new or complementary legislation comprehensively to implement the TPNW. Niue adopted national legislation in 2021 specifically to implement the TPNW.

Mexico was the first state to ratify the 1967 Treaty for the Prohibition of Nuclear Weapons in Latin America and the Caribbean (Treaty of Tlatelolco). It is also the treaty depositary. According to Mexico’s Federal Constitution, all ratified international treaties, such as the Treaty of Tlatelolco and the TPNW, are part of the law of the land. Existing provisions of its criminal law largely address the prohibitions established in the TPNW, but Mexico is elaborating a comprehensive ‘Non-proliferation Law’, which will include complementary provisions on the implementation of the TPNW.
Saint Kitts and Nevis has informed the Nuclear Weapons Ban Monitor that it intends to adopt specific implementing legislation on the TPNW. Currently, many of the Treaty’s prohibitions are effectively covered by the country’s 2002 Anti-Terrorism Act.3 But the new legislation would seek also to cover the TPNW’s positive obligations, which are not addressed by existing laws in force in Saint Kitts and Nevis.4 It had hoped to adopt the new legislation in 2022, but this was not achieved.
The Gambia has also stated that it intends to take measures to give effect to the TPNW at domestic level. The Gambia already has ‘a self-imposed moratorium on the development, production, use, transfer of nuclear material (e.g. uranium) and provision of assistance to the development, production, transfer or use of nuclear weapons or their key components’.
New national legislation should be adopted by each state party to the TPNW that does not yet have in place laws to criminalise the acts prohibited by the Treaty and, where necessary, to implement its positive obligations. Most non-nuclear-armed states are already today implementing most of the core prohibitions of the TPNW. As illustrated by the table below, this is because they pursue nuclear-weapon-free security policies and are states parties to the Treaty on the Non-Proliferation of Nuclear Weapons (NPT), the Comprehensive Nuclear-Test-Ban treaty (CTBT), and the nuclear-weapon-free zone (NWFZ) treaties, and because they have brought into force safeguards agreements with the International Atomic Energy Agency (IAEA). Typically, therefore, they already have in place appropriate national measures, including legislation that addresses all or at least some of the core obligations under the TPNW. Accordingly, the adoption of new national legislation to implement the TPNW may not be necessary.
Crucially, however, all states parties to the TPNW have to establish whether their existing national laws would make it illegal for a national or any other person under their jurisdiction or control to develop, produce, possess, control, transfer, or use nuclear weapons, or to assist any other person to do so, and whether they could prosecute them. If the answer is a clear yes, they have the required national legislation. In most states, engaging in conduct prohibited by the TPNW would ordinarily be a crime even if it is not specifically outlawed, because the handling of dangerous substances (which would encompass nuclear material) is prohibited. Another reason why a state party may not see the need to adopt new legislation is that in many cases (those with a monist constitutional law system), a ratified international treaty may automatically become part of national law.
That said, the Ban Monitor recommends that all states parties adopt dedicated legislation to implement the TPNW. This can also be the simplest and best solution, rather than undertaking a complex mapping of existing legislation. To the knowledge of the Ban Monitor, to date only states parties Ireland and Niue have adopted national legislation specifically to implement the TPNW.
Administrative measures
Beyond the adoption of legislation, other measures, including of an administrative nature, need to be taken to implement the Treaty. Clear instructions should for instance be given to a state party’s diplomats to promote adherence to the Treaty among other states. Preparation may also be needed within government for how to respond to requests for international cooperation and assistance from other states parties. In particular, clear instructions should be given to the administrators of the national health system to ensure the provision of assistance to any victims of nuclear-weapons use or testing who are resident in each state party. For some states, there may also be a need for national measures to enable environmental remediation of affected land.
Algeria, which has signed but not yet ratified the TPNW, issued a prime ministerial decree already in May 2021 that created and mandated a National Agency for the rehabilitation of the former French nuclear test sites in the south of Algeria. The Agency is empowered to contract and manage rehabilitation works and to seek national and international assistance for these operations.1
- Article 5 of the TPNW obligates every state party to take ‘the necessary measures’ to implement its obligations under the Treaty.
- Paragraph 2 of Article 5 stipulates that the duty to implement the Treaty nationally includes the taking of ‘all appropriate legal, administrative and other measures, including the imposition of penal sanctions, to prevent and suppress’ any prohibited activity. It concerns any such prohibited activity whether it is undertaken by natural or legal persons under its jurisdiction or control or on territory under its jurisdiction or control.
- Appropriate criminal legislation should cover at the least all of the core prohibitions set forth in Article 1 of the Treaty.
- The International Committee of the Red Cross (ICRC) has developed and published a model law for common-law states which can serve as a valuable basis for states parties to the TPNW to draft and enact such legislation.
- The CTBT and the CWC also require national implementation measures, but there is no such obligation in the NPT or the NWFZ treaties.