1.  A nuclear weapon (often referred to as an atomic bomb) exists in the arsenal of states as a means of deterrence to prevent war. As weapons of mass destruction, ‘nuclear weapons are explosive devices whose energy results from the fusion or fission of the atom [and] have the potential to destroy all civilization and the entire ecosystem of the planet’ (see Advisory Opinion on the Legality of the Threat or Use of Nuclear Weapons (1996) 226 para. 35; see also Annex II of Protocol No. III on the Control of Armaments (23 October 1954); see also Nuclear Weapons Advisory Opinions). The first use of nuclear weapons was in the theatre of conflict in Hiroshima and Nagasaki, Japan by the United States (‘US’) in 1945. Since the bombing of Hiroshima and Nagasaki, other states have acquired nuclear weapons. The states that have declared their nuclear weapons are the US, Russia, France, the United Kingdom (‘UK’), China, India, Pakistan, and to some extent North Korea. The state of Israel has not declared possession of nuclear weapons. By the end of January 2014, the combined nuclear warheads of both the US and Russia were 9,085, or 4,785 for the US, and 4,300 for Russia (see SIPRI Yearbook (2014) 288–299).

2.  The description of nuclear weapons by the International Court of Justice (‘ICJ’) excludes the delivery methods such as inter-continental ballistic missiles (‘ICBMs’) and also what the ICJ calls ‘highly complex and controversial technological, strategic and scientific information’ (Advisory Opinion on the Legality of the Threat or Use of Nuclear Weapons 226 para. 15) that nuclear weapons systems may entail. Given that nuclear warheads must be capable of delivery by various mechanisms, an essential part of nuclear weapons are the vehicular delivery systems that can either be mobile, land-based, air and seaborne, capable of travelling across continents. As such, states have also acknowledged that nuclear weapons can be tactical (non-strategic) or strategic (PS Morris). The use of nuclear weapons to bomb Hiroshima and Nagasaki has been deemed illegal by a Tokyo District Court in 1963 (see Victims of Atomic Bomb v Japan (Shimoda) (1963) (Japan)). This decision was one of the first attempts to address the legality of nuclear weapons in a domestic court (Falk).

3.  In recent times, North Korea in its constitution reportedly embraces nuclear weapons as a form of self-defence. It has been unverified that a 2012 amendment of North Korea’s constitution refers to the country as a ‘nuclear state’. An inference from such declaration is that nuclear weapons, where they are available in North Korea, are a means of self-defence or tied to the national security of North Korea. In Europe, only France and the UK possess nuclear weapons. A number of North Atlantic Treaty Organization (NATO) member countries, however, host tactical nuclear weapons on their territories as part of NATO’s broader security blanket.

4.  The use of nuclear weapons can be determined either by powers conferred on the legislative body or the president/prime minister. For instance, a parliament would on most occasions be required to give its consent to engage in war, yet, at the other end, the head of the executive may unilaterally engage in war without the consent of parliament. The use and authorization of nuclear weapons in war would then be inferred from the war powers of the commander-in-chief.

5.  The authority to use nuclear weapons (during war) is a highly political matter. For example, in the UK the authority to use nuclear weapons is the prerogative of the Cabinet and prime minister, and the role of parliament is contentious. Although there was parliamentary approval for the UK’s involvement in the Iraq War in 2003 (see House of Commons Hansard Debates (2003) vol. 401, col 760 (UK)) in order to dismantle Iraq’s presumed weapons of mass destruction programme, the practice of parliamentary approval for military conflicts varied over the years.

6.  In the US, war powers rest with the president and the Congress, but the authority to use nuclear weapons rests generally with the president. The division of war powers between the president and the Congress remains opaque and as such, questions on the use of nuclear weapons are still very much political questions.

7.  In other countries such as France, the explicit authority to use nuclear weapons is the domain of the president of the French Republic and such authority is set by decree (see Decree No. 64-46 Relating to the Strategic Air Forces (14 January 1964) Art. 1 (Fr)).

8.  The constitutions of most states prohibit the production of and use of nuclear weapons generally in line with international conventions (see the Non-Proliferation Treaty (1968) (‘NPT’)). For example, nuclear weapons are explicitly prohibited under the Constitution of the Kingdom of Cambodia: 21 September 1993 (as Amended to January 2008) (Cambodia). On the other hand, the constitutions of some states refer to a right to produce elements necessary for the production of nuclear weapons, such as fissile material. The Constitution of the Russian Federation: 12 December 1993 (as Amended to 21 July 2014) Art. 71(i) (Russ) refers to the right to produce ‘nuclear fissile material’.

9.  Constitutions with provisions relating to nuclear weapons usually endorse one of two legal principles: (1) non-proliferation, and (2) self-defence.

10.  Most of the constitutions in Latin America, Asia Pacific, and Africa relate to nuclear weapons through the principle of non-proliferation, and those provisions were adopted into their constitutions following amendments to recognize nuclear- weapons-free zones or the general non-proliferation principle in international law through the NPT. The main aims of the NPT regime on nuclear weapons are the elimination of nuclear weapons (Arts I and II NPT) and disarmament (Art. VI), but the regime also protects states’ right to use of nuclear energy for peaceful purposes (Art. IV NPT). These are the three main pillars of the NPT, and since its indefinite extension in 1995 the NPT has become the most important nuclear weapons treaty, with 191 states parties participating in the treaty. The NPT encourages the elimination of nuclear weapons through domestic constitutions or quasi-constitutional statutes.

11.  Nevertheless, states may also argue that they are constitutionally obliged to develop nuclear weapons as a means of self-defence, or that they have a right to strike first with nuclear weapons. The principle of self-defence is incorporated (or implied) in the war powers granted to the executive and the legislature. This is generally the situation in the US where the power to declare war may include the use of nuclear weapons.

12.  A number of constitutions prohibit nuclear weapons or the trade and development of nuclear material. Countries with constitutions that explicitly prohibit nuclear weapons tend to be either located in a designated nuclear-weapons-free region, or those countries have enshrined the prohibition of nuclear weapons in their constitutions as part of their international obligations under the NPT and other international treaties.

13.  The designated nuclear-weapons-free zones that are provided for by international treaties are: Latin America under the 1967 Treaty for the Prohibition of Nuclear Weapons in Latin America (Treaty of Tlatelolco); Africa under the 1996 Treaty on the Nuclear Weapon Free Zone in Africa (Pelindaba Treaty); South East Asia and the Pacific under the 1995 Treaty on the South East Asia Nuclear Weapons Free Zone (Bangkok Treaty) and the 1985 South Pacific Nuclear Free Zone Treaty (Rarotonga Treaty); and Central Asia under the 2006 Treaty on a Nuclear Weapon Free Zone in Central Asia (Semipalatinsk Treaty or CANWFZ Treaty). These treaties are in conformity with the NPT (Art. VII) that calls for nuclear-weapons-free zones.

14.  The following sections list constitutional provisions which either prohibit the development of nuclear weapons, or provide for the development of nuclear activity for peaceful purposes.

15.  Most of the Latin American countries explicitly prohibit nuclear weapons in their constitutions, for example: Bolivia (Constitution of the Pluri-National State of Bolivia: 25 January 2009, Art. 344(i) (Bol)); Venezuela (Constitution of the Bolivarian Republic of Venezuela: 15 December 1999, Art. 129 (Venez)); Paraguay (Constitution of the Republic of Paraguay: 20 June 1992 (as Amended to 8 November 2011), Art. 8 (Para)); Dominican Republic (Constitution of the Dominican Republic: 28 November 1966 (as Amended to 20 July 2002), Art. 67(2) (Dom Rep)); Columbia (Constitution of the Republic of Colombia: 5 July 1991 (as Amended to 4 November 2011), Art. 81 (Colom)); Mexico (Political Constitution of the United Mexican States: 5 February 1917 (as Amended to 24 February 2017) Art. 27 (Mex)); Ecuador (Constitution of the Republic of Ecuador: 28 September 2008 (as Amended to 7 May 2011) Art. 15 (Ecuador)).

16.  The Constitution of the Federative Republic of Brazil: 4 October 1988 (as Amended to 14 December 2017) Art. 21(XXIII)(a) (Braz)) notes that: ‘all nuclear activity within the national territory shall be allowed for peaceful purposes and shall be subject to approval by the National Congress’. This provision reflects Article 18(1) of the Tlatelolco Treaty, which calls upon Member States to ‘carry out nuclear explosions of nuclear devices for peaceful purposes’. In addition to Article 21 of the Brazilian Constitution, Article 22 confers powers on the Union to legislate ‘nuclear activities of any nature’, whilst Articles 49, 177, and 225 cover the involvement of the executive, nuclear material, and nuclear reactors respectively. Similarly, the Nicaraguan Constitution explicitly mentions the prohibition of nuclear weapons in accordance with international law, see Political Constitution of the Republic of Nicaragua: 19 November 1986 (as Amended to 29 January 2014) Art. 5 (Nicar):

17.  A similar provision is in Ecuador’s constitution (Art. 416). These provisions on the explicit prohibition of nuclear weapons in Latin American countries allow for compliance with international treaty obligations and also demonstrate that the prohibition of nuclear weapons is a constitutional principle as a form of safeguarding human nature with constitutional rights. The constitutional prohibition of nuclear weapons in Latin America provides for cooperation among countries in the region to address concerns that may give rise to nuclear production in the region. These constitutional provisions are safeguards against developing nuclear weapons and are of great significance for countries in the region.

18.  Similar provisions based on the NPT principle or nuclear-free-weapon zones treaties can be found in constitutions in the Asia Pacific and Australasia region. For instance, the Constitution of the Kingdom of Cambodia: 21 September 1993 (as Amended to January 2008), Art. 54 (Cambodia), notes that: ‘[t]he manufacturing, use and storage of nuclear, chemical or biological weapons shall be absolutely prohibited’. The Constitution of the Republic of the Philippines: 2 February 1987, Art. II (s8) (Phil) also establishes a prohibition of nuclear weapons and explains that: ‘[t]he Philippines, consistent with the national interest, adopts and pursues a policy of freedom from nuclear weapons in its territory’.

19.  Other Asian states such as Myanmar link the issue of nuclear weapons in their constitution to defence and security. According to Schedule One, Point 1(d) of the Constitution of the Republic of the Union of Myanmar: 29 May 2008 (Myan), ‘atomic energy, nuclear fuel and radiation and mineral resources essential to its production’ are vital part of Myanmar’s defence and security policy that the state can legislate in. There is no mention of nuclear weapons; however, Point 1(e) states that the country can declare war and conclude peace providing that the Assembly ‘enact laws for the entire or any part of the Union related to matters prescribed in Schedule One’ (Art. 96). In Point 1(c), which list weapons, nuclear weapons are not specifically mentioned; however, other weapons such as ‘arms, ammunition and explosives including biological and chemical weapons’ are areas in which the state can legislate.

20.  For Japan (Constitution of Japan: 3 November 1946 (Japan)), Article 9 notes that ‘[o]ther war potential will never be maintained’. This provision in the Japanese Constitution can be interpreted flexibly to include a prohibition on nuclear weapons, as Article 9 renounces war. Japan’s history with acquiring nuclear weapons has been a constitutional problem due to the pacifist nature of its constitution (McNelly). In 1957, the Cabinet Legislation Bureau pressed to declare that ‘Japan’s Constitution allowed the country to possess nuclear weapons’ (Samuels and Schoff 237). However, by 1967 Japan committed itself to the Three Non-Nuclear Principles: not to (1) introduce nuclear weapons, (2) manufacture, or (3) possess nuclear weapons through a non-binding resolution. Nevertheless, since 2015 a number of statutes enacted in Japan empower the Japanese government the right to collective self-defence (Hasebe (2016)).

21.  The prohibition of nuclear weapons in New Zealand is contained in various pieces of legislation such as the New Zealand Nuclear Free Zone, Disarmament, and Arms Control Act (1987) (NZ) (‘New Zealand Nuclear Free Zone Act’). New Zealand does not have a single constitutional document (although reference must be made to New Zealand’s Constitution Act of 1852, as Amended (NZ)), but a series of legislative acts. The 1987 Act prohibits the acquisition, stationing, and testing of nuclear explosive devices. Although the Act reflects treaties that prohibit nuclear weapons in general, an interesting feature of the New Zealand Nuclear Free Zone Act is that it also prohibits nuclear powered ships from entering New Zealand internal waters (Section 11).

22.  In 1999, Austria enacted the Federal Constitutional Act for a Nonnuclear Austria (‘Austrian Constitutional Nuclear Act’), prohibiting the manufacture, storage, transport, testing, and stationing of nuclear weapons in Austria. Unlike similar provisions in other constitutions in relation to nuclear-weapons-free zones, the Austrian Constitutional Nuclear Act of 1999 explicitly prohibits ‘facilities for stationing nuclear weapons’ (Section 1). What this means is that tactical, strategic, or other form of nuclear weapons cannot be based in Austria by military alliances. The Act also prohibits the procurement of energy ‘by nuclear fission’ (Section 2).

23.  The Iraqi Constitution is one of the newest constitutions to embrace the prohibition of nuclear weapons (Constitution of the Republic of Iraq: 15 October 2005 (Iraq)). Article 9 notes that:

24.  However, it is essential to note that the Iraqi Constitution was written after the second US–Iraq War (2003–2008) that begun because of claims that Iraq was manufacturing weapons of mass destruction including nuclear weapons.

25.  The US and Russia have constitutional provisions that either explicitly or implicitly refer to the use of nuclear weapons.

26.  The Constitution of the Russian Federation: 12 December 1993 (as Amended to 21 July 2014) (Russ), in Article 71(i), explains that the Russian Federation shall have jurisdiction over ‘federal power-engineering systems, nuclear power, fissile materials’. What is interesting about this provision is that, as opposed to ‘nuclear weapons’, the Russian Constitution refers to one of the main materials for nuclear weapons—‘fissile material’. It is also important to bear in mind that the Constitution of the Russian Federation stipulates in Article 15(4) that international treaties to which the Russian Federation is signatory form part of its domestic law (legal system). This appears to be contradictory to the provision in the Russian Constitution that recognizes nuclear power and fissile material (broadly nuclear weapons). Nevertheless, there is a provision in the Russian Constitution that refers to the ‘armed forces’ that must be borne in mind, as they are broad enough to cover the constitutionality of the use of nuclear weapons by the Russian Federation. That provision is Article 87(1), which acknowledges the president as the supreme commander-in-chief of the armed forces. While this provision is standard in some constitutions, it provides the Russian president the right to engage, if attacked, the possibility of using nuclear weapons, as part of his response.

27.  In the Constitution of the United States of America: 17 September 1787 (US), there are two provisions that are often interpreted as also referring to nuclear weapons: Article 1, Section 8, regarding Congressional authorization for the use of force; and the Second Amendment right to bear arms. These two provisions are seen as collectively including nuclear weapons. US courts have confirmed that, should the president act pursuant to an ‘implied authorization of Congress, his authority is at its maximum’ (see Youngstown Sheet and Tube Company v Sawyer (1952) 635 (US)), including the right to use nuclear weapons.

28.  According to Article I, Section 8, Clause 11 of the US Constitution, ‘[t]he Congress shall have Power … to declare war’. The president, on the other hand, per the constitution, can ‘repel sudden attacks’. The War Powers Resolution, 87 Stat. 555 (1973) (US) also empowers the president to deploy armed forces to combat zones and then inform Congress. Thus, according to the War Powers Resolution, the president can respond to ‘a national emergency created by an attack upon the United States’ (types and effects of emergency).

29.  The key to interpreting this part of the War Powers Resolution is to determine whether a national emergency warrants a response with a nuclear counter-attack, or, in the case of an attack by a nuclear weapon, the president may deploy nuclear weapons to repel sudden attacks without informing Congress. While the different provisions of the US Constitution delegate power to Congress including the declaration of war and, broadly, acquiring nuclear weapons, the president enjoys power to repel sudden attacks. Where the US Congress declares war, weapons at the disposal of the president such as nuclear weapons are seen as within the confines of the Constitution, should the president decide to use nuclear weapons in war.

30.  However, the War Powers Resolution is not so clear, when it comes to defining the scope and extent the president may authorize the use of nuclear weapons. Although the US Constitution in general grants both the US Congress and the president the powers to engage in armed conflicts, there is no explicit legislation or judicial opinions that authorize the president to use nuclear weapons in armed conflicts. Although Article II of the US Constitution grants the president broad powers as commander-in-chief of the armed forces, there is still uncertainty if those broad powers also include the use of nuclear weapons. This lack of clarity in the US Constitution on the president’s authority to conduct war––in particular, war that involves the use of nuclear weapons––suggests that any use of nuclear weapons may be unconstitutional. Although some US courts have suggested that the president ‘possesses emergency authority to use military force to defend the nation from attack’ (Campbell v Clinton (2000) (US), Tatel, J, concurring), the extent of such emergency authority does not seem to suggest the use of nuclear weapons. Thus, in short, the vagueness of the US Constitution and the unwillingness of the courts to recognize the president’s authority to first use nuclear weapons, suggests that, constitutionally, it is a shared power in the US — to be decided simultaneously. Nevertheless, under the War Powers Resolution, it appears that the president may respond to an attack with nuclear weapons where it is evident that such attack creates a national emergency and it is his role to repel such attack.

31.  Outside of constitutions, nuclear activities may be regulated by other legislative acts and policy documents. For instance, Libya’s Resolutions of the 9th Libyan General People’s Congress: 16 February 1984 (Libya) under Article II.D(III)(ii) condemned the Italian government for placing ‘nuclear missiles’ in southern Italy in direct firing line of Libya. However, in a similar resolution a year earlier it was declared that through Libya’s membership of the United Nations an objective was to ‘work to halt the nuclear arms race which is threatening mankind with destruction’ (Partial Text of Final Drafts of the Resolutions of the Basic People’s Congresses as Relayed from the Final Session of the 8th General People’s Congress in Tripoli: 17 February 1983, Art. 4(5)(c) (Libya)).

32.  Another document that specifically mentions nuclear weapons is the Declaration on the State Sovereignty of Ukraine: 16 July 1990 (Ukr). According to Article IX, ‘[t]he Ukrainian SSR solemnly declares its intention to become a permanently neutral state that will not join any military blocs and will abide by three non-nuclear principles: not to accept, not to practice, and not to seek the acquisition of nuclear weapons’ (neutrality). The Constitution of Ukraine: 28 June 1996 (as Amended to 21 February 2014 (Ukr)) underscores the need to coordinate Ukraine’s national interests and security ‘according to generally acknowledged principles and norms of international law’ (Art. 18). This provision can be interpreted to also refer to nuclear non-proliferation principles in international law, echoing Ukraine’s Declaration on State Sovereignty.

33.  However, one of the most interesting developments from a state perspective and nuclear weapons was when Mongolia unilaterally declared its territory a nuclear-weapons-free zone in 1992. The United Nations (UN Doc A/55/56–S/2000/160 (29 February 2000)) have acknowledged Mongolia’s legislation on its nuclear-weapon-free status (Law of Mongolia on its Nuclear-Weapon-Free Status (2000) (Mong)). As a unilateral act by a sovereign state, the Mongolian declaration and subsequent law of 2000 is one of the first to prohibit nuclear weapons via ‘constitutional-like legislation’ not linked to the traditional treaty regime of nuclear weapons free zones.

34.  Other legislation on nuclear activities in various nuclear weapons armed states relates to the associate activities of nuclear weapons programmes. Legislative acts in the UK include the Nuclear Installations Act 1965/57 (as Amended) (UK); the Radiological Protection Act (1970) (UK); the Radioactive Substances Act (1993) (UK); and the Energy Act (2013) (UK).

35.  Similar to the UK, in the Russian Federation a number of legislative acts exist that regulate various aspects of nuclear activities both in the civilian and military sphere. These include Federal Law No. 170-FZ of 21 November 1995 on the Use of Atomic Energy (as Amended to 1 December 2007) (Russ); Federal Law No. 102-FZ of 26 June 2008, on Ensuring the Uniformity of Measurements (as Amended to 28 July 2012) (Russ); and Federal Law No. 3-FZ of 9 January 1996, on Public Radiation Safety (as Amended to 17 July 2011) (Russ). In addition, there are a number of decrees (ordinances), rules, guidelines, and safety requirements that are associated with nuclear activities in the Russian Federation, which are to be taken into account when interpreting the core legislations or constitutional provisions on nuclear weapons and activities.

36.  Policy doctrines that also regulate the use of nuclear weapons include the US Department of Defence ‘Nuclear Posture Review’ (2018) (US) and the Military Doctrine of the Russian Federation, Approved by the President on 25 December 2014, No. Pr. - 2976 (Russ).

37.  Courts have long grappled with questions on nuclear weapons. Given that nuclear weapons form part of the security and defence apparatus of states, courts are limited in terms of how they can address questions on nuclear weapons (see for example John v Donnelly (1999) (Scot); Victims of Atomic Bomb v Japan (Shimoda), Tokyo District Court (1963) (Japan) (‘Shimoda’). In Shimoda, the Tokyo District Court for instance raised questions on the constitutionality of nuclear weapons; however, the decision by the court was to find that nuclear weapons were illegal under international law, as opposed to the claims for damages the plaintiffs were seeking under the Japanese Constitution. In another case, Gibbons v Salii (1987) (Palau), the Pacific nation of Palau ruled that the nuclear prohibition provisions of the Palau Constitution applied to ships in transit that were nuclear-capable.

38.  Although international treaties and conventions exist that prohibit or ban the use of nuclear weapons, some states continue to see nuclear weapons as part of their strategic defence apparatus and are willing to circumvent international rules to own or possess nuclear weapons. In its 1996 Advisory Opinion, the ICJ did not conclude that nuclear weapons or their possession are illegal under international law:

39.  It did, however, acknowledge that the ‘possession of nuclear weapons may indeed justify an inference of preparedness to use them’ (para. 48).

40.  The challenge for nuclear arms treaties is not so much the norms they create in international law. Rather, it is a matter of how disciplined states are in complying with nuclear treaties and whether the constitutional provisions in their domestic constitutions reflect the major pillars of the NPT. Some constitutions replicate international treaties that call for nuclear-weapons-free zones, whilst other constitutions require authorization for the use of nuclear weapons. Some constitutions clearly state the right to acquire and possess weapons including nuclear weapons. For other states, their constitution recognizes that they are a ‘nuclear weapons’ state. In this regard, the way national constitutions treat acquiring weapons or nuclear weapons does matter, as they confer how such weapons would be deployed in armed conflicts.

41.  What is crucially relevant based on the constitutional legal framework of most states that recognize or have acquired nuclear weapons, is that constitutional recognition of nuclear weapons governs any other legal relationship that may develop in the legislative process where certain laws pertaining to nuclear weapons or other ‘nuclear use’ are enacted. Furthermore, in relation to nuclear weapons treaties, in constitutions such that as the US where treaties are ‘part of the supreme law of the Land’ (Art. VI(2)), they are seen as having the same status as legislation that Congress enacts and are to be interpreted within the spirit of the constitution (see also dualism / monism). In general, it may be said that nuclear weapons are legal within a domestic setting and nuclear-weapons-armed states can use nuclear weapons during times of war as part of their self-defence; however, only under conditions that are at minimum out of ‘necessity’ and ‘proportional’ to an armed attack (Military and Paramilitary Activities in and Against Nicaragua (Nicaragua v United States) (1986) para. 176; Military and Paramilitary Activities in and against Nicaragua Case (Nicaragua v United States of America)).