Revisiting Non-Compliance in the JCPOA: A Legal and Procedural Clarification in Favor of Iran-Dr. Jabbar Aslani

Dr. Jabbar Aslani - University Lecturer of International Law
2025/08/6

The Joint Comprehensive Plan of Action (JCPOA), signed in 2015 between Iran and the P5 1 (China, France, Germany, Russia, the United Kingdom, and the United States), aimed to restrict Iran’s nuclear activities in exchange for the lifting of international sanctions. However, accusations of “non-compliance” have complicated the agreement’s implementation, especially following the U.S. withdrawal in 2018. This note revisits the concept of non-compliance under the JCPOA and United Nations Security Council Resolution 2231 (2015), providing a legal and procedural clarification in favor of Iran. The analysis argues that the main breach lies with the United States, not Iran, and that Iran’s subsequent steps were within the bounds of its rights under the deal.

1. Introduction

The JCPOA is a political agreement with legal implications, endorsed by UNSC Resolution 2231 (2015). It is not a treaty under international law but imposes reciprocal obligations. The U.S. withdrawal in May 2018 and its subsequent reimposition of sanctions on Iran triggered a series of retaliatory measures by Tehran. This sequence has raised questions about the legal interpretation of "non-compliance" and the legitimacy of actions by both parties. This paper argues that Iran’s actions after the U.S. withdrawal constitute lawful remedial measures under the JCPOA, and that the primary non-compliance originates from the United States.

2. Legal Nature of the JCPOA

The JCPOA is a multilateral agreement under international law, albeit not a legally binding treaty in the classical sense. It was endorsed by UNSC Resolution 2231, which gives it a unique legal character. According to the Vienna Convention on the Law of Treaties (VCLT), even non-binding instruments may generate legal consequences when they are incorporated into binding frameworks or when the parties act upon them consistently and with reliance.

UNSC Resolution 2231 “endorses” the JCPOA and calls upon all UN Member States to support its implementation. It also contains a “snap-back” mechanism in case of significant non-performance, which can reimpose prior sanctions. Thus, while the JCPOA may not be a formal treaty, it is enveloped within a binding legal framework due to its endorsement by the Security Council.

3. The U.S. Withdrawal: Breach of Obligations

The United States’ unilateral withdrawal from the JCPOA in May 2018 under the Trump administration was a direct violation of its commitments under the deal. Paragraphs 18 and 29 of the JCPOA make clear that the United States committed to lifting nuclear-related sanctions and to refrain from imposing new nuclear-related sanctions. Furthermore, UNSC Resolution 2231 called on Member States to refrain from actions that would undermine the implementation of the JCPOA.

The International Court of Justice (ICJ) has repeatedly held that withdrawal from agreements cannot be done arbitrarily if such action undermines international obligations (e.g., Namibia Advisory Opinion, 1971; Nicaragua v. United States, 1986). The U.S. reimposition of sanctions violated the principle of pacta sunt servanda and eroded the mutual trust essential for performance of the JCPOA.

Additionally, the U.S. withdrawal triggered a cascading effect, deterring European and other actors from engaging with Iran economically—an effect termed “secondary sanctions.” This frustrated Iran's legitimate expectation of economic benefit under the JCPOA.

4. Iran’s Response: Legal Justification of Remedial Measures

Following the U.S. exit and failure of European parties to implement effective economic mechanisms (like INSTEX), Iran began reducing its commitments under the JCPOA in 2019. These reductions were carried out in stages and under paragraph 36 of the JCPOA, which allows a party to “cease performing its commitments under the JCPOA in whole or in part” if it believes another party is not meeting its obligations.

This self-declared dispute resolution mechanism was never exhausted prior to the U.S. withdrawal, but Iran attempted to use it afterward. Iran notified the Joint Commission and allowed timeframes before each step, consistent with the procedural requirements of paragraph 36.

Iran's measures included:

• Exceeding uranium enrichment levels beyond 3.67%.
• Increasing stockpiles of low-enriched uranium beyond 300 kg.
• Installing and using more advanced centrifuges.

While these measures go beyond the strict limits of the JCPOA, they are reversible and were clearly presented as responses to the breach by another party. Under general principles of international law, such as exceptio non adimpleti contractus (non-performance by one party justifies non-performance by the other), Iran’s steps are legally defensible.

5. Misinterpretation of “Non-Compliance” and the Political Narrative

Western discourse, particularly that of the United States, frequently labels Iran as “non-compliant” without acknowledging the triggering breach. This framing ignores the sequence of events and the legal principle of proportionality in international agreements.

The International Atomic Energy Agency (IAEA) has acknowledged Iran’s deviations but also recognized the context, noting Iran’s transparency in inspection and verification. In fact, the IAEA continued to have access to Iranian nuclear facilities for a significant time after the U.S. withdrawal, which indicates Iran's willingness to cooperate despite political pressure.

Furthermore, the claim by the United States in 2020 to initiate the “snap-back” mechanism under Resolution 2231, despite no longer being a party to the JCPOA, was legally untenable and rejected by the vast majority of the Security Council. This affirms that the U.S. cannot benefit from a legal instrument it has repudiated.

6. Procedural and Legal Clarification in Favor of Iran

Iran’s position is further reinforced by the procedural deficiencies in the U.S. conduct. According to the JCPOA, disputes must be resolved via the Joint Commission and an Advisory Board, with ample opportunities for dialogue and remediation. The U.S. not only bypassed these steps but also sought to undermine the deal entirely through a policy of “maximum pressure.”

Legally speaking, Iran remained within the JCPOA framework longer than was required. After more than a year of diplomatic patience and failed promises from the European parties, Iran’s decision to reduce its commitments can be viewed as lawful countermeasures—not violations.

The concept of countermeasures, under the International Law Commission’s Articles on State Responsibility (2001), allows a state to suspend performance of its obligations temporarily in response to a prior internationally wrongful act, provided the response is proportionate and reversible. Iran's actions fit squarely within this doctrine.

7. Conclusion

The label of “non-compliance” as applied to Iran is not only misleading but legally flawed. The JCPOA’s architecture explicitly allows parties to adjust their commitments in response to breaches by others. Iran’s response to the U.S. withdrawal was legally and procedurally consistent with its rights under the JCPOA and general international law.

The primary non-compliance lies with the United States, whose unilateral withdrawal and reimposition of sanctions constituted a material breach of its obligations. Iran’s calibrated responses—reversible, transparent, and procedurally notified—reflect restraint rather than defiance.

A balanced legal reading of the JCPOA and UNSC Resolution 2231 thus supports Iran’s position and underscores the need for objective legal standards rather than politicized interpretations in resolving such complex international agreements.