The role of national and international courts in compliance and enforcement

Under certain circumstances, national and international courts also play a role in enforcing non-proliferation and disarmament treaties, such as those related to biological, chemical and nuclear weapons. In international law, the principle of sovereign equality of all states applies, which means that no state may sit in judgment over another state. What states are allowed to do, however, is to hold individuals accountable and prosecute them and, in certain instances, turn to the International Court of Justice to settle disputes with other states. However, there are limitations to the possibility of enforcement especially at the international level.

National courts

The production, possession and use of nuclear, chemical and biological weapons is a criminal offence in many countries. National courts can thus hold individuals involved in such activities criminally liable. This applies if the offence is committed on the country’s own territory (= territoriality principle), or in another country but the offender or the victim is a national of the state that initiated criminal proceedings (= active and passive personality principle, respectively). Lastly, some states have adopted legislation providing their national courts with universal jurisdiction, which applies irrespective of the location of the crime or the nationality of the perpetrator or victim, provided that the crime in question is particularly abhorrent, such as war crimes, including the use of biological or chemical weapons, or crimes against humanity (principle of universality). Generally, because of the principle of immunity, national courts cannot hold state bodies of a foreign state liable for their role in such crimes if they acted in their official capacity. However, with regard to the most serious crimes, interpretation of the rules of immunity of state bodies under international law has varied between various national courts.

One example is the case of the French magistrate who, on 14 November 2023, issued an arrest warrant for Syria’s President, Bashar al-Assad. According to the court, there was sufficient evidence to initiate proceedings against President al-Assad for his key role in numerous chemical weapons attacks. However, there was a legal dispute about the question of al-Assad’s immunity as then sitting head of state, which may now move in a new direction since al-Assad’s fall from power in December 2024. Proceedings were still in progress as of December 2024.

International courts

The International Criminal Court (ICC) could also play a role in punishing individual offences related to crimes such genocide, crimes against humanity, war crimes and the crime of aggression (see Article 5 et seq. of the Rome Statute).

The ICC has jurisdiction if such a crime has been committed on the territory of a state party (principle of territoriality), or if it has been committed outside such territory but the perpetrator is a citizen of a state party (principle of active personality). Moreover, the ICC can exercise jurisdiction if the UNSC has referred a situation to the Court. In this case, the concept of universal jurisdiction applies. As for the enforcement of ICC rulings, states are obliged to extradite to the Court a person who it has indicted. In contrast to national courts, the ICC does not differentiate between crimes committed by a state body in their official or private capacity or by a private person.

Essentially, all the crimes listed above can be committed with biological and chemical weapons, for example if they are used in an armed conflict to deliberately kill civilians. However, although the Rome Statute uses the same language as the 1925 Geneva Protocol regarding the use of asphyxiating gases and poisonous weapons, among other things, it is not clear whether the Statute originally directly applied to the use of biological or chemical weapons. In 2017, the use of biological weapons was explicitly designated a war crime under the jurisdiction of the ICC in both international and non-international armed conflicts. However, the pertinent amendment to the Rome Statute has only entered into force for those 23 states that had ratified it as of December 2024. The ICC has not yet passed a judgment dealing with biological, chemical or nuclear weapons.

Theoretically, it is also possible for proceedings to be initiated before the International Court of Justice (ICJ).¹ Unlike the ICC, the ICJ is responsible for legal disputes between states. However, it can only exercise its jurisdiction under very specific conditions, most of which presuppose states actively and explicitly accepting the ICJ’s jurisdiction either generically, based on international treaties or for specific cases. As for enforcement, the decisions of the ICJ are generally non-executable. Because states are sovereign and only voluntarily agree to the ICJ’s jurisdiction, they cannot ultimately be forced to abide by its rulings. The only option is for other states or the ICJ itself to increase the political pressure on these states or try to persuade them to comply with international law by means of sanctions.

Despite these limitations, the ICJ has acted several times in relation to non-proliferation and disarmament treaties. In 1994, the UNGA requested that the ICJ issue an advisory opinion on the question of whether the threat or use of nuclear weapons is under any circumstances permitted under international law. The Court’s opinion, issued in 1996, did not definitively conclude whether the use of nuclear weapons would be illegal in extreme situations of self-defence, but it held that the use of nuclear weapons would most likely contradict core principles of humanitarian law. In 2014, the Republic of the Marshall Islands filed an application with the ICJ, claiming that the United Kingdom had breached treaty and customary international law obligations concerning negotiations relating to nuclear disarmament. While the ICJ did not assume jurisdiction in the case, it reiterated that Article VI of the NPT comprises a specific obligation for states parties, including the nuclear weapons states, to actively pursue nuclear disarmament. Neither action is a classic example of enforcement. However, the political impact of the ICJ’s statements in both cases can be seen as strengthening the normative basis of nuclear disarmament and incentivising states to abide by their treaty obligations. In another example, in June 2023, Canada and the Netherlands initiated ICJ proceedings against the Syrian Arab Republic under the UN Convention against Torture, claiming that Syria had violated numerous provisions of international law during its civil war, including through the use of torture and other types of cruel, inhuman or degrading treatment or punishment and the use of chemical weapons.² As of December 2024, the case was still pending.

Footnotes

1. See also Dunworth, Treasa, note 1. ↩

2. Hoffberger-Pippan, Elisabeth/de Vries, Barry. 2023. Chemical Attacks under the Convention against Torture: A New Possible Avenue? PRIF Blog, 21 August, available at: https://blog.prif.org/2023/08/21/chemical-attacks-under-the-convention-against-torture-anew-possible-avenue/ ↩