international law

Autonomous Weapons Systems and Proportionality – New Article

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Published a new law review article, “Autonomous Weapons Systems and Proportionality: The Need for Regulation,” in the Case Western Reserve Journal of International Law, Vol. 57:1 (2025). The full text is available for download at SSRN here, and the abstract is below:

This article examines the question of whether International Humanitarian Law (IHL) requires modification to effectively govern autonomous weapons systems (AWS). While extensive scholarly discourse has focused on whether AWS can comply with existing IHL principles, and whether the development and deployment of AWS should be constrained through weapons treaties, insufficient attention has been paid to why and how IHL itself might need adaptation to regulate AWS as a method of warfare. Given that the imminent development and deployment is unlikely to be prohibited, and that AWS may not comply with IHL in certain circumstances, the question of why and how IHL needs to be adjusted is important. The analysis focuses on the principle of proportionality as a means of exploring and illustrating the issue.

The article first traces the evolution of AWS governance debates, highlighting the impasse at the Convention on Certain Conventional Weapons (CCW) regarding constraints on AWS development. It then conducts a detailed examination of the distinct elements and operation of the principle of proportionality, a principle whose implementation demands complex, contextual, and sophisticated judgment.

The article examines the evidence of certain weaknesses of AI-operated AWS, explains why the operationalization of the principle of proportionality would present challenges for such systems, and argues that AWS would likely struggle to implement the principle reliably and predictably in certain operational contexts. The final section supports and defends proposals for the certain adjustments or modifications of IHL to better regulate AWS, thereby ensuring AWS operations remain constrained by the core principles of IHL. It ends by briefly exploring the mechanisms that might be available for developing such constraints.

The Power of Rights-Based Climate Change Litigation

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My law review article exploring the influence and impact of rights-based climate change litigation has now been published in the Case Western Reserve Journal of International Law, and the full article can be downloaded from SSRN. The abstract is posted below:

An increasing number of legal challenges to government climate change policies are being advanced on the basis that states are violating the human rights or constitutional rights of applicants. A number of high-profile cases in Europe have upheld such claims and ordered governments to adjust their policies. But questions remain regarding how effective such rights-based cases may be in the effort to enforce climate change law obligations or encourage government responses to the crisis. This Article explores how such rights-based cases may exercise greater influence than is typically understood.

After explaining briefly the relevant human rights and climate change law, this Article examines in some detail a sample of rights-based climate cases that reflect a common pattern of features that provide the basis for such an explanation. The cases illustrate the incorporation of both international human rights law norms, and international climate change law obligations and standards, which are used to assess the legitimacy of government climate change policy. The courts increasingly rely upon the science of climate change institutions and the arguments and doctrines developed by foreign courts and international tribunals, including new doctrines for rejecting typical “drop in the ocean” causation and justiciability arguments traditionally relied upon to dismiss climate change cases.

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What was the International Legal Basis for the Strike on al-Zawahiri?

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(Published in Just Security, Aug. 9, 2022)

The killing of al-Qaeda leader Ayman al-Zawahiri in a CIA drone strike has been touted as a political win for President Joe Biden, a vindication for an over-the-horizon counter-terrorism strategy, and even as “justice served.” Yet there appears to be little interest in whether it was lawful. The media has not seriously raised the question, the punditry has not addressed it, and the government has not yet provided any official legal basis for the killing (to be fair, some law and policy blogs, such as Lawfare, Just Security, and Articles of War, have begun to address it). This disregard is problematic, as there are indeed serious questions as to the lawfulness of this strike – and people should be demanding answers.

Let us acknowledge up front that Ayman al-Zawahiri was the second-in-command of al-Qaeda at the time of the 9/11 terrorist attacks on the United States – which were heinous crimes, terrorist acts, and amounted to an “armed attack” against the United States under international law.

Nevertheless, his killing some 21 years later requires a legal justification under international law. What is more, the drone strike also constituted a use of force against Afghanistan, with which the United States is no longer engaged in an armed conflict – and so that too requires legal justification. This essay briefly reviews the international law regimes that are implicated (leaving aside entirely the domestic law considerations, such as the 2001 Authorization for Use of Military Force), and some of the questions regarding the lawfulness of the strike that arise under each regime – and argues that these questions are important.

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Why Canada Should Rethink its Approach to Economic Sanctions

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(Published in The Conversation, Mar. 6, 2022)

Western countries have imposed massive sanctions against Russia for its invasion of Ukraine. The West has increasingly relied on economic sanctions to punish or change the policies of foreign governments in the last several decades. The conventional wisdom is that economic sanctions are an effective and peaceful foreign policy tool.

Some sanctions regimes, such as the current effort against Russia, may be both effective and lawful. But as I explored in a recent research report, some economic sanctions may violate international law principles, including those the sanctions are intended to enforce. They may therefore undermine the very legal regimes that Canadians like to champion.

The nature of economic sanctions

Many economic sanctions are authorized by the United Nations Security Council or regional organizations. But countries are increasingly imposing sanctions without such legal authority. It’s these so-called unilateral or autonomous sanctions that raise legal questions.

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