On July 13, 2023, the International Court of Justice (ICJ) delivered its judgment in the case concerning Question of the Delimitation of the Continental Shelf Between Nicaragua and Colombia Beyond 200 Nautical Miles from the Nicaraguan Coast (Nicaragua v. Colombia) (2023 Judgment). This is the first decision addressing the question of the delimitation of the continental shelf, between states with opposite coasts, in a situation where one state asserts a continental shelf extending beyond 200 nautical miles (extended continental shelf) within the 200 miles from the baselines of another state.

On March 29, 2018, the Government of the Co-operative Republic of Guyana (hereinafter Guyana) filed in the Registry of the Court an application instituting proceedings against the Bolivarian Republic of Venezuela (hereinafter Venezuela) with respect to a dispute concerning “the legal validity and binding effect of the Award regarding the Boundary between the Colony of British Guiana and the United States of Venezuela, of 3 October 1899” (hereinafter the 1899 Award or the Award).

On December 1, 2023, the International Court of Justice (ICJ) delivered a unanimous order on provisional measures in Arbitral Award of 3 October 1899 (Guyana v. Venezuela) (Provisional Measures Order). The ICJ indicated two provisional measures. It ordered first that, pending a final decision in the case, Venezuela shall refrain from taking any action that would modify the situation that currently prevails in the relevant disputed territory (the current situation being that Guyana administers and exercises control over the territory) and, second, that both states shall refrain from any action that might aggravate or extend the dispute before the ICJ.

On June 19, 2023, the Intergovernmental Conference on an international legally binding instrument under the United Nations Convention on the Law of the Sea on the conservation and sustainable use of marine biological diversity of areas beyond national jurisdiction (BBNJ Intergovernmental Conference) adopted, by consensus, the Agreement under the United Nations Convention on the Law of the Sea on the Conservation and Sustainable Use of Marine BioLogical Diversity of Areas Beyond National Jurisdiction (BBNJ Agreement or Agreement). The Agreement, which is grounded in and builds on the UN Convention on the Law of the Sea (UNCLOS), specifically addresses issues relating to the conservation and sustainable use of the marine biodiversity of the high seas. The adoption of the Agreement was the culmination of nearly two decades of work under the auspices of the UN General Assembly.

On January 31, 2024, marking the tenth anniversary of the Russo-Ukrainian war, the International Court of Justice (ICJ) delivered its eagerly anticipated judgment on the merits in Ukraine v. Russia concerning alleged violations of the International Convention for the Suppression of the Financing of Terrorism (ICSFT) and the International Convention on the Elimination of All Forms of Racial Discrimination (CERD). This was the first case lodged by Ukraine against Russia back in 2017, in response to alleged numerous violations arising from Russia's occupation of Crimea and its proxy war in Donbas. Although Ukraine might have hoped for a more favourable outcome, the majority only established narrow and rather minor violations under ICSFT and CERD, despite a plethora of claims advanced by Ukraine under both Conventions. A 13:2 majority found that Russia violated Article 9, paragraph 1 of ICSFT due to its failure to investigate individuals who allegedly committed terrorism financing offences upon receiving the information from Ukraine. As for CERD, another 13:2 majority found that Russia violated Articles 2, paragraph 1(a), and 5(e)(v) of the Convention with regard to the implementation of school education in the Ukrainian language in Crimea. In addition, an 11:4 majority found that Russia violated the provisional measures order, which obliged Russia to lift restrictions on the Mejlis, the highest representative executive organ of Crimean Tatars in Crimea banned by Russian authorities, and imposed the non-aggravation measure. The judges were divided on the scope of the non-aggravation measure, and questioned the appropriateness of establishing the violation of the provisional measures order in part concerning the Mejlis in the absence of the majority's finding of the corresponding violation under CERD on the merits.

On March 24, 2023, the UN Committee on Enforced Disappearances (the Committee or CED) delivered its unanimous “Views adopted under art. 31 of the [International Convention for the Protection of All Persons from Enforced Disappearances],” concerning communication no. 4/2021 on Mexico. The decision relates to the disappearance of Yonathan Isaac Mendoza Berrospe on December 11, 2013, in the city of Veracruz, Mexico. The decision determined that he was a victim of enforced disappearance and that the state failed to guarantee the rights to an effective search, a prompt and effective criminal investigation, and reparations, including the right to know the truth. The Committee considered that his mother was also a victim of the violation of her rights.

On May 21, 2024, the International Tribunal for the Law of the Sea (the Tribunal) delivered a unanimous advisory opinion on the Request submitted to the Tribunal by the Commission of Small Island States on Climate Change and International Law. This was the first advisory opinion on climate change obligations issued by an international judicial body, and the first of three anticipated advisory opinions on climate change obligations from international judicial bodies. The request had been submitted on December 12, 2022 by the Commission of Small Island States on Climate Change and International Law (COSIS). Two questions on obligations of states parties under the United Nations Convention on the Law of the Sea (UNCLOS) were posed in the request: (1) what are the specific obligations to prevent, reduce, and control pollution of the marine environment in relation to the deleterious effects that result, or are likely to result, from climate change and ocean acidification, which are caused by anthropogenic greenhouse gas (GHG) emissions into the atmosphere; and (2) what are the specific obligations to protect and preserve the marine environment in relation to climate change impacts and ocean acidification. A total of 34 states parties to UNCLOS and nine intergovernmental organizations submitted statements, and 33 states parties and four intergovernmental organizations made statements during the oral proceedings.

Following a debate at the Parliamentary Assembly of the Council of Europe (PACE) on January 26, 2023 (7th sitting), under the urgent procedure, a text was adopted by 100 votes in favour, none against, and one abstention: a Resolution on the “Legal and human rights aspects of the Russian Federation's aggression against Ukraine.”

Over the course of the period from the end of 2022 to early 2023, requests for advisory opinions on climate change were, for the first time, made to the International Court of Justice (ICJ), the International Tribunal for the Law of the Sea (ITLOS), and the Inter-American Court of Human Rights (IACtHR).

On July 18, 2023, the Appeals Chamber, by a 3–2 majority, rendered its “Judgment on the appeal of the Republic of the Philippines against Pre-Trial Chamber I's ‘Authorisation pursuant to article 18(2) of the Statute to resume the investigation.’” The decision upheld the Pre-Trial Chamber's decision of January 26, 2023, which authorized the Prosecutor to resume investigating crimes within the jurisdiction of the Court allegedly committed on the territory of the Philippines between November 1, 2011 and March 16, 2019, in the context of a government-led “war on drugs” campaign.

On February 2, 2024, the International Court of Justice (the Court) delivered its preliminary objections judgment in the case brought by Ukraine against Russia under the Convention on the Prevention and Punishment of the Crime of Genocide (the Genocide Convention).

The international struggle against impunity for perpetrators of atrocities, including genocide, crimes against humanity, and war crimes, has been a key interest of the international community since the end of World War II. Many achievements have been accomplished with respect to international collaboration on the “substantive issues” of international criminal law (ICL), such as defining and criminalizing the core crimes of international law, yet collaboration on the procedural and practical aspects of ICL, known as mutual legal assistance (MLA) has been neglected.

On July 6, 2023, the Court of Justice of the European Union (CJEU) delivered its judgment in C-663/21 AA on a preliminary reference from the Austrian Supreme Administrative Court. The CJEU examined the international legal principle of non-refoulement and how it applies in EU law, particularly to expulsion decisions following the withdrawal of refugee status. It held that EU law “preclude[es] the adoption of a return decision in respect of a third-country national where it is established that removal of that third-country national to the intended country of destination is, by reason of the principle of non-refoulement, precluded for an indefinite period.”

On January 17, 2023, the Grand Chamber of the Court of Justice of the European Union (CJEU) delivered its judgments in case C-632/20, P Spain v. Commission (Kosovo), ruling that notwithstanding the European Union's non-recognition of Kosovo as a state, Kosovo may participate in an EU agency, namely the Body of European Regulators for Electronic Communications (BEREC). The judgment is significant for several reasons: (1) for the European Union's growing engagement with non-recognized territorial entities since it clarifies the meaning of the concept of “third country” and confirms that such entities may participate in EU agencies; (2) for the European Union's engagement with Kosovo—particularly in the light of Kosovo's 2022 bid for EU membership; and (3) more broadly, in the context of the burgeoning debate regarding the CJEU's approach to international law.

On January 9, 2024, the U.S. Ninth Circuit Court of Appeals issued a decision in Cassirer v. Thyssen-Bornemisza Collection Foundation. The case concerned ownership of a U.S. $30 million painting that had been stolen by the Nazis from its Jewish owner. More than six decades later, the pre-War owner's grandson discovered that the painting was on display in a Spanish museum and sought to reclaim it. The matter was in litigation in U.S. courts for almost twenty years. The outcome eventually turned on the issue of choice of law. The court's holding that Spanish law should apply resulted in a judgment that the defendant was the legal owner of the artwork. The court's decision is also notable for a concurring opinion asserting that the defendant should have voluntarily returned the painting to the plaintiffs in accordance with Spain's commitment to the Washington Conference Principles on Nazi-Confiscated Art (Washington Principles).

In its 75th ordinary session, the African Commission on Human and Peoples’ Rights (ACHPR, or Commission), the human rights organ of the African Union, with a mandate to promote and protect human and peoples’ rights and interpret the African Charter on Human and Peoples’ Rights, unanimously adopted the African Guiding Principles on the Human Rights of Migrants, Refugees and Asylum Seekers (Guiding Principles). They were publicly launched by the Commission at its 77th ordinary session on October 21, 2023. The drafting was led by the Commission's Special Rapporteur on Refugees, Asylum Seekers, Internally Displaced Persons, and Migrants in Africa. The thirty-eight Guiding Principles are based largely on African regional treaty law, case law, standards, and resolutions of the Commission and also draw from complementary international law. In addition, the Guiding Principles draw from the experience of other world regions, including adoption by the Inter-American Commission on Human Rights (the human rights organ of the Organization for American States) of the 2019 Inter-American Principles on the Human Rights of All Migrants, Refugees, Stateless Persons, and Victims of Human Trafficking.

On December 7, 2023, the Court of Justice of the European Union (CJEU) delivered its judgment on a preliminary ruling under Article 267 TFEU from a request of the Verwaltungsgericht Wiesbaden (Administrative Court, Wiesbaden, Germany). The CJEU examined the interpretation and application of Article 22 of the General Data Protection Regulation (GDPR) regarding automated individual decision-making, including profiling, in the context of the probability values (or scorings) that are made to evaluate and predict the future payment capacity of individuals when they request credits to financial institutions.

Under Article 41 of the UN Charter, the Security Council has established 31 sanctions regimes since 1966. Sanctions measures encompass a broad range of enforcement actions not involving the use of armed force. The measures have ranged from comprehensive economic and trade sanctions to more targeted measures such as arms embargoes, travel bans, and financial or commodity restrictions. In recent years, there have been increasing numbers of complaints from humanitarian organizations that sanctions cause or exacerbate humanitarian crises. The UN Office for the Coordination of Humanitarian Affairs (OCHA) has estimated that at least 222 million people were experiencing acute food insecurity at the end of 2022, the largest global food crisis in modern history. At the same time, the countries that need the most assistance are often subject to international sanctions regimes. As of March 2023, UN sanctions applied in nine of the top ten operations of the International Committee of the Red Cross.

On May 23, 2024, the Fifth Section of the Court issued its judgment in Saakashvili v. Georgia concerning the immunity of former Georgian President Mikheil Saakashvili from prosecution for acts committed while in office. After giving up his Georgian citizenship and becoming a Ukrainian national, Saakashvili was convicted in absentia in two separate sets of criminal proceedings against him and was sentenced to a total of six years in prison. As part of a larger effort to make reparations for past wrongdoing, the Georgian Government received over 20,000 complaints from people claiming to be victims of serious human rights violations committed during the rule of Saakashvili's political party, the United National Movement, and under his presidency. The first case concerned a July 2005 attack on a member of parliament who was forced out of his car, beaten by several men, and was left permanently disfigured. The member of parliament alleged that the attack was retaliation for an interview he gave in which he spoke negatively about Saakashvili and his wife. The second case concerned Saakashvili's pardoning of four former high-ranking officials of the Ministry of the Interior who had been convicted of murder. That led to a separate investigation being opened in 2014 to explore charges of abuse of power.

On December 19, 2023, the Svea Court of Appeal in Sweden issued its judgment in the above case affirming the conviction and sentencing of Hossein Seyed Ahmadi, an Iranian citizen, for grave breaches of international humanitarian law and murder that took place in Iran in 1988. Specifically, he was charged with having executed prisoners associated with the People's Mojahedin Organization of Iran in the Gohardasht prison. Though the Court of Appeal dismissed the conviction of grave breaches of IHL with regard to some of the prisoners at issue, it found overall that the district court was correct in holding that the prosecutor substantiated the charges levied against Ahmadi. With regard to the murder charge, the Court of Appeal affirmed and noted that it should actually have been considered several acts of murder instead of just one single act. One judge dissented and argued that the defendant should have been found guilty of aiding and abetting murder rather than murder itself. The Court of Appeal also agreed with the district court's assessment that the acts took place in relation to the conflict between Iran and Iraq, thus triggering the application of IHL. Ahmadi's sentence to life in prison stands, and damages have been awarded to surviving plaintiffs and relatives of the deceased prisoners.