Applicability of “Snapback” Mechanism: Can E3 Snap back the UN Security Council Sanctions on Iran?-Dr. Hossein Khalaf Rezaee

Dr. Hossein Khalaf Rezaee - Attorney at law and legal advisor and University lecturer <arselna@gmail.com >
2025/08/07

The snapback mechanism was established through UN Security Council Resolution (UNSCR) 2231, which endorsed the 2015 Iran nuclear deal.  The U.N. ambassadors of Britain, Germany and France (the E3) wrote in a Dec. 6 letter 2024 to the Security Council that they are ready - if necessary - to trigger a so-called “snapback” of all international sanctions on Iran that would otherwise lapse this October. 

“In full accordance with paragraph 36 of the Joint Comprehensive Plan of Action, the E3 triggered the dispute resolution mechanism in January 2020 in response to Iran’s violation of its commitments. Since then, we have striven in good faith to resolve the issues arising from Iran’s non-compliance through this procedure. Iran’s significant non-compliance remains unresolved, allowing the E3 to treat the unresolved issue as grounds to cease performing their commitments under the Joint Comprehensive Plan of Action in whole or in part, as allowed by the Joint Comprehensive Plan of Action. It is on this basis that the E3 did not lift sanctions on Iran’s nuclear and ballistic missile programmes on Transition Day in October 2023, in full accordance with the Joint Comprehensive Plan of Action and with Security Council resolution 2231 (2015). We reiterate that this was a proportionate and legitimate response to years of Iran’s non-compliance with its commitments.” they said.

The main question is whether the E3 can trigger the snapback mechanism. This is not abstract question and we need to bear in the mind that if the JCPOA as an agreement (even though, political one) has defeated its object and purpose, whether because of the US withdrawal from the JCPOA or because of the very fact that the parties to the JCPOA not adhering to its essential commitments, as far as, speaking at a press conference in Tokyo, IAEA Director General Rafael Grossi described the JCPOA as “an empty shell”.

The JCPOA as a Bilateral or Multilateral Agreement?

The JCPOA was an agreement between Iran and the P5 1 countries (with the presence of a representative of EU), whereby, Iran has accepted some commitments, and in return, the other party, i.e., a group known as E3/EU 3 has undertaken some commitments as well. These commitments are owed not individually to a particular State but to a collective, a group of States. So, it seems that the JCPOA is a bilateral agreement, not a multilateral one. Therefore, when one member of such a group withdraws from the agreement (i.e., the United States), the group’s identity as a Party to the agreement ceases to exist. Therefore, with the withdrawal of the United States and the breakdown of the P5 1 composition—effectively transforming it into the P4 1—the JCPOA, as an agreement, was effectively terminated, even though the remaining participants have continued to voluntarily adhere to its provisions. Accordingly, the snapback mechanism, as a component of the JCPOA, can no longer be invoked.

The Reciprocal Nature of the JCPOA and Its Implications 

Fitzmaurice well stated that, treaties of the “reciprocating type” are those “providing for a mutual interchange of benefits between the parties, with rights and obligations for each involving specific treatment at the hands of and towards each of the others individually”. (Third Report on the Law of Treaties by Gerald Fitzmaurice, UN doc. A/CN.4/115, para. 2.) Pursuant to Article 60(1) of the Vienna Convention on the Law of Treaties (VCLT), “A material breach of a bilateral treaty by one of the parties entitles the other to invoke the breach as a ground for terminating the treaty or suspending its operation in whole or in part.” The JCPOA commitments are divided into two categories: (1) confidence-building measures by Iran regarding its nuclear program, and (2) the lifting of sanctions by the P5 1 group. The essence of such an agreement lies in the reciprocal nature of these undertakings—each party's commitment is given in exchange for a corresponding obligation by the other. In other words, the contractual balance between rights and obligations—namely, the interdependence between Iran’s compliance with its nuclear commitments and the lifting of sanctions—constitutes the very raison d'être of the JCPOA.

As noted by the ministers of the Joint Commission of the JCPOA in their statement of July 6, 2018: “The participants recognised that, in return for the implementation by Iran of its nuclear-related commitments, the lifting of sanctions, including the economic dividends arising from it, constitutes The meaning of this statement is that, in the event of non-compliance by the E3 with their commitments, Iran may treat such a breach as a ground to cease performing its own obligations under the JCPOA, either in whole or in part. Therefore, such a response by Iran should not be considered a violation of the agreement, but rather a lawful reaction to the other party’s breach.

The Requirements for Triggering “Snapback” Mechanism

Paragraph 36 of the JCPOA provides that “if the complaining participant deems the issue to constitute significant non-performance, then that participant could treat the unresolved issue as grounds to cease performing its commitments under this JCPOA in whole or in part and/or notify the UN Security Council that it believes the issue constitutes significant non-performance”. “Upon receipt of the notification from the complaining participant, as described above, including a description of the good-faith efforts the participant made to exhaust the dispute resolution process specified in this JCPOA, the UN Security Council, in accordance with its procedures, shall vote on a resolution to continue the sanctions lifting. If the resolution described above has not been adopted within 30 days of the notification, then the provisions of the old UN Security Council resolutions would be re-imposed, unless the UN Security Council decides otherwise.” (Paragraph 37 of the JCPOA)

Accordingly, the basic requirements for triggering the snapback mechanism are twofold. First, a JCPOA participant state must believe that another participant is failing to meet its commitments under the JCPOA in a manner that constitutes significant non-performance. Second, the referring state must demonstrate the good-faith efforts it made to exhaust the dispute resolution process outlined in the JCPOA.

While the first criterion may be relatively uncontroversial, the second raises more serious questions—particularly as the E3 has reiterated, at the very moment of the expiration (sunset) of Resolution 2231, a claim originally made in January 2020 regarding Iran’s alleged non-performance since 2019. However, in recent years, there has been no substantial change in Iran’s position with respect to its compliance with the JCPOA.

Conclusion

The United States’ withdrawal from the JCPOA and its reimposition of sanctions, along with the E3’s refusal to lift arms and missile sanctions eight years after the JCPOA’s implementation—effectively amounting to a reimposition of such sanctions—provide Iran with grounds to partially or fully cease performing its related commitments under the JCPOA. This response can be justified by the provisions of the agreement itself.

As noted above, the E3 claimed to have triggered the dispute resolution mechanism in January 2020. However, they did not exhaust the procedure outlined in paragraph 36 of the JCPOA. Instead, they chose to stop performing their own obligations under the agreement, notably by failing to lift ballistic missile sanctions on Transition Day in October 2023. Even assuming the E3 had a legal basis for this decision, paragraph 26 of the JCPOA allows Iran to treat the reimposition of sanctions as a valid ground to cease the performance of its commitments, in whole or in part.

Given the reciprocal nature of obligations under the JCPOA, Iran’s reduction in compliance cannot be regarded as a violation of the agreement, as it was a direct response to: (1) the United States’ unilateral withdrawal and reimposition of sanctions, including those targeting Iran’s ballistic missile program (as listed in Annex II of Resolution 2231), and (2) the E3/EU’s failure to lift economic sanctions in accordance with paragraph 29 of the JCPOA. Ultimately, once the E3 declined to lift ballistic missile sanctions pursuant to paragraph 20 of Resolution 2231—eight years after Adoption Day—Iran’s non-performance of its JCPOA commitments cannot, by any reasonable legal standard, be considered unlawful.

It is worthy to note what was the International Court of Justice in its Advisory Opinion of 21 June 1971 made it clear that: “One of the fundamental principles governing the international relationship thus established is that a party which disowns or does not fulfil its own obligations cannot be recognized as retaining the rights which it claims to derive from the relationship.” (ICJ Reports 1971, para. 91.)