On the “Whims of Foreign Courts”

When a Dutch appeals court in 2024 halted the export of F-35 parts to Israel by the Netherlands, because of the risk that these parts would be used in the commission of serious breaches of international humanitarian law (IHL) in Gaza, Marco Rubio, then still a US senator, quickly reacted on X, saying that US “military abilities shouldn’t be subjected to whims of foreign courts.”

The ruling by another “foreign court” last week may be more to Mr Rubio’s liking: the UK High Court decided that the UK can continue to issue licences for F-35 components that go into a pool of spare parts which Israel can use on its existing F-35 jets. The finding by the High Court that the UK cannot exclude Israel as an end user for UK manufactured components because “the only way for the UK to ensure that its components do not reach Israel is for it to suspend all exports into the F-35 programme” (para 177) raises pertinent questions with regard to the UK’s compliance with the Arms Trade Treaty (ATT) and other key provisions of international law.

What’s more, its factual findings in this regard, which were partly based on closed evidence, also say something – albeit indirectly – about the compliance with international law by the other European states participating in the programme (Denmark, Netherlands, Italy). As such, the judgment may have implications for pending cases regarding F-35 exports in Denmark and the Netherlands, countries that have directly incorporated international legal obligations in their domestic systems and that are, unlike the UK, also bound by the EU Common Position.

What is the F-35 Carve Out?

In September 2024, the UK Secretary of State for Business and Trade suspended arms export licences for items that might be used by Israel in the war in Gaza. The decision was taken because the Government had concluded Israel was not committed to complying with IHL and therefore a clear risk existed that UK exported items could be used to commit or facilitate serious violations of IHL. However, one exception was made: the suspension did not apply to licences for components for F-35 fighter jets, provided that those components would not be specifically identified as having Israel as an end-user. This decision, aka the F-35 carve out, was based on advice from the Defence Secretary and the Foreign Secretary.

According to the Defence Secretary, due to the nature of the partnership laid down in the (undisclosed) 2021 Memorandum of Understanding between the UK and the US, it was not possible to suspend licensing for F-35 components for use by Israel, without having an impact on the entire F-35 programme. A suspension of licensing for all F-35 nations would disrupt global supply chains, harm NATO capabilities, and damage the UK’s credibility with allies, as the UK was (after the US) the largest national provider of components to the multinational F-35 programme. The Foreign Secretary acknowledged the existence of a clear risk that military equipment exported to Israel might be used to commit or facilitate serious violations of IHL. Nonetheless, he also supported the carve-out due to the programme’s critical importance to the security of the UK, its allies, and NATO, as well as wider international security.

Challenging the F-35 Carve Out

The claimant, the Palestinian NGO Al Haq, together with interveners Oxfam, Amnesty International, and Human Rights Watch, brought a challenge to the F-35 carve out, arguing that the Secretary of State for Business and Trade had acted unlawfully under domestic and international law. As regards international legal obligations, the claimant appealed to Common Article 1 of the Geneva Conventions, Articles 6 and 7 ATT, and Article I of the Genocide Convention, as well as to customary international law, in particular the customary law obligations to ensure respect for the Geneva Conventions, to prevent genocide and not to aid or assist in internationally wrongful acts (Articles 16 and 41 of the ILC Articles). All of these rules entailed, according to the NGOs, an obligation to halt the export of arms if the exporting state had knowledge that the arms would be used to commit serious violations of IHL or genocide, or if a clear risk existed of such crimes.

Al Haq also claimed that the decision was taken ultra vires under the UK Export Control Act 2002, seeing that it risked facilitating criminal offences by the Israeli military and even UK factory workers as accessories under domestic law (Geneva Conventions Act 1957 and the International Criminal Court Act 2001). Moreover, the NGOs argued that the decision was based on an irrational assessment of the impact of a suspension of F-35 licences, as the UK could simply have informed the operators of the global F-35 spares pool that “any UK manufactured parts must not be provided to Israel” (para 168). A last claim concerned the unreasonableness of the decision, as the Secretary of State had not considered the particular seriousness of the violations of IHL when balancing the risk of those violations on the one hand with strategic and political considerations on the other.

The High Court’s take on the F-35 Carve Out

The judgment by the High Court is 72 pages long, so it is impossible to do justice to its extensive reasoning here. A large part is dedicated to the scope and intensity of the court’s review against principles of domestic constitutional law, such as dualism, sovereignty of parliament, executive powers over matters of defence, national security, and foreign relations. These principles entail that a UK domestic court has no jurisdiction to interpret or apply unincorporated treaties, except if there would be a “domestic foothold”, for example, because domestic law refers directly to international legal obligations (paras 72-109). When it comes to norms of customary international law, the situation is different as common law should be in alignment with it (para 125). But in the case of customary international law as well, its reception in domestic law should be consistent with constitutional principles mandating judicial deference over decisions of the executive (para 130-135).

The High Court emphasised that the issues of international law arising are “contentious” (para 116), and it ruled that claims regarding the unlawfulness of the F-35 carve out, which refer directly or indirectly to international law, are not justiciable. This was the case, either because there was no foothold in domestic arms export law for the unincorporated Treaty obligations that the claimant invoked (para 122); or because the international law obligations that the claimant invoked were not such that they should constrain executive decision making in areas that are the responsibility of the executive and not of the courts (paras 112 and 134-135).

A key consideration of the Court in this context is that the content of the international legal obligation to “ensure respect” for the Geneva Conventions “in all circumstances” is disputed, with “substantial differences of practice and opinion within the international community on the question whether Common Article 1 requires a state to ensure respect for the Conventions by other states as distinct from by other persons or entities within or subject to a state’s jurisdiction” (para 131, see also 47-50). In the same way, the High Court questions the precise content of the obligation to prevent genocide (para 132).

After it concluded that the F-35 carve out could thus not be reviewed against international legal obligations, the High Court decided that it didn’t need to determine whether there is a significant risk that the carve out may facilitate the commission of offences under UK law on international crimes, as that was not the aim of domestic arms export law (paras 137-166). It then turned to the question of whether the Secretary of State, in allowing for the carve out, took an irrational decision. It looked at the “highly integrated” nature of the F-35 programme, which “is simply not designed to enable any of the Participants to make unilateral decisions” (para 173). Any instruction to the spares pool or the assembly lines that UK components are not to be used in Israeli F-35s would require the consensus of all the partners (para 174). Based on closed evidence, the court accepted “that there was no realistic possibility of persuading all other partner nations that F-35 exports to Israel should be suspended” (para 180). As such, the only alternative to the F-35 carve out was complete withdrawal from the programme with damaging defence and diplomatic consequences. As such, the decision was not deemed irrational.

Arms trade and the duty to ensure respect for IHL and to prevent genocide

The High Court qualifies the question whether (customary) international law contains an obligation to ensure respect for IHL by other states (as distinct from by other persons or entities subject to a state’s jurisdiction), as “a contentious question of international law” (para 131, see also paras 47-51). Similarly, when it comes to the obligation to prevent genocide, the Court considers “the content of that obligation and in particular the extent to which one state is required to take action, and if so what action, to prevent the commission of genocide by another state” as unclear (see para 132). However, the Court’s conclusion that it is contentious whether there exists a customary law obligation that prescribes a state’s behaviour towards third states, is not tenable, neither in general nor in the specific context of arms trade with Israel.

In its Advisory Opinion on the Construction of a Wall in 2004, the International Court of Justice (ICJ) gave an authoritative interpretation of the pertinent IHL obligation: “States parties to the Geneva Convention relative to the Protection of Civilian Persons in Time of War of 12 August 1949 are under an obligation […] to ensure compliance by Israel with international humanitarian law as embodied in that Convention” (para 159). This unequivocal positive obligation towards other states was reaffirmed and extended to obligations under the Genocide Convention by the ICJ in its 2024 Order in Nicaragua v Germany.

Even though the ICJ did not indicate provisional measures in the latter case, it reminded Germany of its international law duties when exporting arms. Thus, the ICJ reaffirmed that, under Common Article 1 of the Geneva Conventions, all States parties are obliged to respect and ensure respect for the Conventions at all times. This duty applies universally, regardless of whether a State is directly involved in a conflict. According to the ICJ, this reflects both the text of the Conventions and fundamental principles of international humanitarian law. Similarly, under the Genocide Convention, States are under an obligation to prevent genocide wherever there is a serious risk, using all reasonable means available, which includes a duty not to commit or assist in the commission of acts listed in Article III of the Convention. The ICJ stressed that States must comply with their international legal obligations regarding arms transfers in conflict situations, therewith avoiding the risk that such weapons could be used to breach international humanitarian or genocide law. It did not indicate the provisional measures requested by Nicaragua, but that decision was based on an assessment of the German case-by-case licensing practice. The ICJ pointed out that “for every licence that is granted, an assessment is carried out by the German Government to ascertain whether there is a clear risk that the particular item subject to licensing would be used in the commission of genocide, crimes against humanity or grave breaches of the four Geneva Conventions,” with the authorities refusing export if such a clear risk existed (para 17 of the Order).

Even the Secretary of State seemed to implicitly accept that there is state practice affirming the obligation for third states to ensure respect for IHL in conflicts to which they are not party. He pointed out that countries such as the US, Canada, and Israel do not agree with this particular interpretation of IHL (para 151), qualifying it as a “minority view”. But that these countries interpret their international law obligations differently is hardly surprising in view of their participation in the F-35 programme. That in itself cannot be an argument for the High Court to avoid serious engagement with the interpretation provided by the ICJ. That there is an obligation to ensure respect by other states for IHL and to prevent genocide by other states is so unequivocal, that the common law should be in conformity with it. The Court seems to confuse the question whether a rule of customary law exists on the one hand, with the complexities with regard to its application in each and every case on the other. Key here is the Court’s failure to distinguish between negative and positive obligations. While the precise extent of the positive obligations involved is arguably open for debate, that is not the case for the negative obligations involved in the context of the arms trade. As such, all the High Court would have to do in this particular case is to interpret the uncontentious negative duty to abstain from providing arms, also indirectly, to a state which is involved in very serious violations of IHL and at risk of violating its obligations under the Genocide Convention.

European compliance with international law in a US-dominated multinational defence project

Concerning the claims by the NGOs relating to the ATT, the High Court ruled similarly: it would need to “determine disputed issues as to the interpretation of [the] Treaty and its application to the facts of the conflict in Gaza” and that was not for a domestic court to do (para 59). Leaving domestic questions of justiciability aside, the factual details provided in the judgment are highly salient as regards the legal conformity of the carve out with the ATT. They make clear that excluding UK F-35 parts for delivery to Israel is practically possible (of course!), but simply not desired by (some of the) other F-35 partners. One doesn’t have to be a clairvoyant to understand the role of the US government, which is “by far the biggest participant” in the F-35 project (para 172) and owner of all components until they are fastened on a particular fighter jet. The US signed the ATT under Obama but never ratified it, with the first Trump administration declaring it had “unsigned” the Treaty.

According to Article 6(3) ATT, a state shall not authorise exports if it has knowledge that arms components will be used to commit or facilitate genocide or grave breaches of IHL. Article 7 ATT applies when such knowledge is absent, prescribing a risk assessment in that case under para 1. It prohibits the export of arms if there is an “overriding risk” that they would be used to commit serious violations of IHL (Article 7(3) ATT). The travaux to the ATT suggest that ‘overriding’ in this context should be read as “overridingly probable” (see the Advocate General opinion to the Dutch Supreme Court and the sources cited there). Therefore, once such a risk exists, states cannot balance it against other considerations, such as those related to foreign policy, national security, or defence.

Hence, the UK carve out is simply in violation of international law, whether it is justiciable before a domestic court or not. The F-35 requires an immense amount of continuous maintenance, and each F-35 has British components in it, with “over 15 percent of the components […] made in the UK, including the rear fuselage, electronics, and ejection seats.” As such, it is more than probable that UK exports to the global spares pool end up in Israel, which uses the jet in the war in Gaza. In any case, under Article 5(2) and (5) of the ATT, the government is required to operate a control system which is effective and transparent.

The British government, however, fails to make the important distinction between domestic justiciability on the one hand and international law compliance of its acts on the other. According to a government spokesperson, the ruling purportedly “showed that the UK operates one of the most robust export control regimes in the world”. Very recently, MP’s have asked the government to clarify its views on the conformity of the F-35 carve out with the UK’s international legal obligations. The government may want to have a look at the ILC Articles on State Responsibility when formulating an answer: international customary law on state responsibility precludes responsibility only on a few limited grounds. Committing the international wrongful act in consortium with other states who cannot be persuaded to alter their behaviour, is – evidently – not one of them.

The factual details about the impossibility of excluding end users in the F-35 supply chain, although some of the specifics are in the closed part of the judgment, are also highly relevant for current litigation in Denmark and the Netherlands, which have similar “carve outs”. These countries are not only bound by the ATT, which is directly incorporated in their domestic law, but also by the EU Common Position. The latter instrument has provided a binding interpretation of the term “overriding risk” in the ATT for the EU Member States: there can be no room whatsoever for the balancing of interests once a “clear risk” has been established (Article 2 para 2 under c). Moreover, Article 5 of the EU Common Position stipulates that export authorizations are granted only on the basis of “reliable prior knowledge regarding the end use in the country of final destination”. When it comes to parts destined for production in third countries, Member States must take particular account of the risk that the final product could be exported to an “undesirable end user”. Currently, both the Netherlands and Denmark emphatically leave open the possibility that the F-35 parts exported by them end up in Israel. As such, allowing these exports constitutes an unambiguous violation of the ATT and of the explicit end-user provisions of the EU Common Position.