Law of War and Armed Conflict

Russia’s 2022 invasion of Ukraine produced a flood of scholarship asking how third states could legally justify providing weapons, funds, and intelligence to Ukraine. That assistance appeared to violate obligations under the venerable international law of neutrality. Many scholars argued that these neutrality “violations” could be justified under the law of state responsibility as either acts of collective self-defense or as countermeasures. Some also invoked the idea of “qualified neutrality,” a controversial principle that exempts states supporting victims of unlawful aggression from otherwise applicable neutrality limitations. This was a critical debate. The law of neutrality has been dormant for decades, especially in the immediate post-Cold War era, when the U.N. Security Council dominated the landscape of international responses to armed conflict. This scholarship sought to reconcile neutrality principles with contemporary law on state responsibility and the use of force and provide clarity in an era when collective measures by the Security Council are all but impossible to achieve.
This article responds to these well-intentioned scholarly accounts and argues that the justifications given for assisting Ukraine are misguided and, ultimately, unnecessary. Neutrality law has never involved binding obligations on third states, even in its nineteenth-century heyday. Neutrality was instead a status; a set of rights and obligations that states could choose to accept if they stayed within its limits. States could also choose to discard those limits and risk becoming parties to the conflict. Understanding neutrality as a status rather than an obligation means there is no need to justify “unlawful” transgressions of neutrality limits under the law of state responsibility. But even if third party assistance to a victim state like Ukraine were unlawful, the justifications of self-defense and countermeasures fail on their own terms. And while invoking “qualified neutrality” may appear more promising, that principle simply begs the question of how law on the use of force would conceive of third party assistance, the grounds of debate that would exist had neutrality law never entered the picture. Qualified neutrality, in other words, does not resolve the lawfulness of third party assistance but instead assumes the issue has been resolved under an entirely different body of international law. The entire effort to avoid neutrality barriers to assisting Ukraine and other victims of aggression turns out to have been a tempest in a teapot.

In paragraph two of its resolution on lethal autonomous weapon systems, pursuant to U.N. General Assembly resolution 78/241, the General Assembly requested the Secretary-General to solicit the views of Member States and Observer States regarding lethal autonomous weapons systems (LAWS). Specifically, the request encompassed perspectives on addressing the multifaceted challenges and concerns raised by LAWS, including humanitarian, legal, security, technological, and ethical dimensions, as well as reflections on the role of human agency in the deployment of force. The Secretary-General was further mandated to submit a comprehensive report to the General Assembly at its seventy-ninth session, incorporating the full spectrum of views received and including an annex containing those submissions for further deliberation by Member States.

In implementation of this directive, on February first, 2024, the Office for Disarmament Affairs issued a note verbale to all Member States and Observer States, drawing attention to paragraph two of resolution 78/241 and inviting their formal input. Corresponding communications—notes verbales and letters—were also disseminated to the entities identified in paragraph three of the resolution, requesting their contributions on the matter.  For the first time, this Article analyzes the positions of States parties on LAWS submitted to the Secretary-General in 2024, pursuant to UN General Assembly Resolution 78/241 calling for the views of Member States and Observer States on lethal autonomous weapons systems, inter alia, “on ways to address the related challenges and concerns they raise from humanitarian, legal, security, technological and ethical perspectives and on the role of humans in the use of force.” The Article focuses on Member States’ positions in relation to human-centric approaches to LAWS and compliance with international humanitarian law. Moreover, it argues that the standard for autonomous weapons systems’ compliance with the laws of war should not only be whether they follow the principles of international humanitarian law of distinction, proportionality, and precaution, but whether they can be free of algorithmic bias. The last several years of data analysis have shown that data bias and algorithmic bias can result in unintended consequences that pose the risk of unlawful discrimination. From housing to finance, mortgage lending to credit worthiness, and college applications to job recruitment, the use of artificial intelligence (AI) can result in unintended consequences that pose the biggest risk to women and minorities. While relying on potentially biased inputs, the “black box” of a machine can magnify these biases in its outputs or decisions. Furthermore, machine learning can help algorithms even learn to discriminate.

AI mistakes are often patterned, reflecting patterns in training data, algorithms, or the AI’s fundamental design. The Article asks whether Yale Law School professor Oona Hathaway’s recent arguments on individual and state responsibility for the patterns of “Mistakes” in War may also apply to the pattern of biases in AI-driven LAWS. In current and future disputes, machines do and will continue to make life-and-death decisions without the help of human decision-making. Who will then be responsible for the “mistakes” in war?

Although much has been written about algorithmic bias, an “algorithmic divide” can create an AI-driven weapons asymmetry between different nation states depending on who has access to AI. In the final analysis, the Article argues that the transformative potential of AI must be harnessed not in conflict but in conflict resolution.

Big data—extremely large quantities of information and the analytics used to process it—is now crucial to the way militaries operate on the battlefield. Data is used to run weapons systems, analyze intelligence, procure and deploy personnel, evaluate battlefield conditions, detain prisoners, and more. And not only is data increasingly being used on the battlefield, but operations targeting adversaries’ data—to acquire it, delete and destroy it, or distort or poison it—are becoming increasingly important as well. Beyond the battlefield, big data lies at the epicenter of adversarial activities below the armed conflict threshold. Because data is the fuel of artificial intelligence (AI), it is generating an AI arms race among the U.S., China, Russia, and other states, incentivizing large-scale cyber operations related to data. And big data is increasingly central to humanitarian operations on, and adjacent to, the battlefield, for example to monitor humanitarian crises, facilitate early warning systems, and deliver aid, as well as to investigate and prosecute atrocities.

All of these uses of data in military operations raise challenging interpretive questions under key bodies of international law: international humanitarian law (IHL), the jus ad bellum and international human rights law (IHRL). But they also challenge us to consider anew various long-standing critiques of legalism in the international sphere more generally: what we might call the efficacy critique—are these laws effective at all in constraining state and non-state actors?—what we might call the legitimation critique—do laws of war actually sanitize, and thereby legitimate, acts of aggression?—and the critique that law is simply ineffective in adapting to rapid technological or societal change.

This Article uses the rise of big data on the battlefield first to respond to these critiques and defend the importance of legalism when addressing armed conflict, and second to consider the multiple interpretive challenges and gaps in the law that are created by the new techno-social reality of big data on the battlefield. As in other instances of disruptive technological and societal change, the laws of armed conflict must be both justified anew and then adjusted, either through textual gap-filling, interpretive translation, policymaking, or the construction of new legal paradigms.

In a potential future peer-on-peer or near peer conflict, the technological capabilities that are both taken for granted and a source of military superiority will be an immediate and high-value target. Global navigation and positioning systems, satellite imaging, precision guidance, instantaneous communication, and much more— the adversary will seek to shut down these capabilities. Turning off the technology, or fighting “in the dark,” presents complex operational and tactical challenges of navigation, logistics, communication, command and control, coordination, and targeting, to name just a few. However, executing military operations in such a technology-deprived environment also requires the application and implementation of the law of armed conflict (LOAC) in the dark, which introduces a set of parallel challenges and concerns.

This Essay explores the challenges for the law when all the technological capabilities that are deeply incorporated into our daily lives and our military operations are not available in armed conflict—because the capabilities have been turned off, jammed, spoofed, or taken down. The law of armed conflict, in contrast, will not be turned off. LOAC applies regardless of capability, type of conflict, or any other distinguishing scenario about a particular conflict. A first challenge lies in the application of LOAC in such situations, including training for the wars the military will need to fight, new questions of interoperability with partners and allies, and a more careful understanding of the relationship between law and policy in the implementation of military operations. Second, the application of LOAC “in the dark” presents the risk of significant pressures on the law as our understandings of and discourse about key principles are put to new tests. Consider proportionality and precautions, for example—current implementation of both core principles of targeting is replete with reliance on technological capabilities that may or will be degraded or rendered unavailable. And yet the absence of those capabilities does not diminish or alter these core legal obligations, highlighting the need to analyze and reaffirm the meaning and application of these fundamental rules. Other pillars of LOAC that will face significant pressure are the role of reasonableness, doubt, and certainty in decision-making and the relationship between capabilities and obligations.

China has upset the security balance in East Asia through the development of a long-range strike complex composed of anti-ship ballistic missiles, drones and cruise missiles, and hypersonic missiles that put U.S. naval fleets at risk. Beijing’s innovative approach to sea control through the projection of power from land-based fires highlights three important differences between the law applicable to naval warfare and the law of armed conflict (LOAC) as it is implemented on land.1 These legal distinctions are subtle in law, but they shape concrete choices available to naval commanders and could determine the outcome of war at sea.

First, the standard for what constitutes a military objective in naval warfare is broader than in land warfare. For example, enemy war-sustaining industries and commercial shipping may be captured or even destroyed in conflict at sea, whereas private property on land is generally protected.

Second, in war on land, commanders must take all feasible precautions in attack to consider alternative methods or means to reduce injury to civilians or civilian objects, a high standard. During armed conflict at sea, only reasonable precautions must be taken. This lower bar makes sense because it is less likely that civilians and civilian objects will be caught up in a naval war. The practical result is that war at sea has fewer precautions.

Third, attacks against military objectives in the law of armed conflict require a proportionality analysis, which operates differently at sea than on land. Those who plan, approve, or execute an attack are subject to the rule of proportionality, which prohibits attacks in which the expected collateral damage is excessive relative to the anticipated military advantage to be gained. Since naval warfare is fought from platforms, such as warships, submarines, and military aircraft, the proportionality analysis includes only civilians or civilian objects near the platform but does not include civilians or civilian objects on board.

These legal nuances would govern any naval conflict between China and the United States and could quickly intensify and widen the conflict.

• Paul Symon & Arzan Tarapore, Defense Intelligence Analysis in the Age of Big Data, 79 Joint Force Q. 5 (2015).
• This Article uses the terms “law of naval warfare” and international law applicable to “war at sea” or “conflict at sea” interchangeably. James Kraska et al., The Newport Manual on the Law of Naval Warfare, 101 Int’l L. Stud. i, xiii (2023).
• For further discussion of these developments, see generally Big Data and Armed Conflict: Legal Issues Above and Below the Armed Conflict Threshold (Laura A. Dickinson & Edward W. Berg eds. 2024) (hereinafter Big Data and Armed Conflict).
• For further discussion of these developments, see generallyid.
• For further discussion of these developments, see generallyid.
• See, e.g., Ashley Deeks, The Double Black Box: National Security, Artificial Intelligence, and the Struggle for Democratic Accountability (2024); Rebecca Crootof, Margot Kaminski, & Nicholson Price, Humans in the Loop, 76 Vand. L. Rev. 429 (2023); Ken Anderson & Matthew Waxman, Debating Autonomous Weapon Systems, Their Ethics, and Their Regulation Under International Law, inThe Oxford Handbook of Law, Regulation, and Technology (2017).
• An important exception is The Rights to Privacy and Data Protection in Times of Armed Conflict (Russell Buchan & Asaf Lubin eds. 2022); see also Big Data and Armed Conflict, supra note 2.
• See Laura A. Dickinson, Translation or Disruption?, International Law, Military Operations, and the Challenges of Big Data, in Big Data and Armed Conflict, supra note 2, at 1, 2.
• See Asaf Lubin, The Duty of Constant Care and Data Protection in War, in Big Data and Armed Conflict, supra note 2, at 229; Ashley S. Deeks, Predicting Enemies, 104 Virginia L. Rev. 1529, 1531 (2018).
• See Lubin, supra note 8.
• See Fionuala Ní Aoláin, The Datafication of Counterterrorism, in Big Data and Armed Conflict, supra note 2, at 319, 335–38.
• See Gary P. Corn & Eric Talbot Jensen, “Attacking” Big Data: Strategic Competition, the Race for AI, and the International Law of Cyber Sabotage, in Big Data and Armed Conflict, supra note Error! Bookmark not defined., at 91, 93–94.
• See Aoláin, supra note 10.
• See Corn & Jensen, supra note 11.
• See François Delerue, Data Centers and International Humanitarian Law, in Big Data and Armed Conflict, supra note 2., at 207.
• Mark A. Visger, Garbage In, Garbage Out: Data Poisoning Attacks and their Legal Implications, in Big Data and Armed Conflict, supra note 2, at 179.
• Seeid.
• Seeid.
• See Stop Autonomous Weapons, Slaughterbots, YouTube (Nov. 12, 2017), https://perma.cc/3LYY-QRSN.
• See Omar Yousef Shahabi & Asaf Lubin, Israel – Hamas 2024 Symposium - Algorithms of War: Military AI and the War in Gaza,Articles of War (Jan. 24, 2024), https://perma.cc/68ZM-NNUT.
• See Noam Lubell & Katya Al-Khateeb, Cyborg Soldiers: Military Use of Brain-Computer Interfaces and the Law of Armed Conflict, in Big Data and Armed Conflict, supra note 2, at 249.
• See, e.g., New Evidence that Biometric Data Systems Imperil Afghans: Taliban Now Control Systems with Sensitive Personal Information, Human Rights Watch (March 30, 2022), https://perma.cc/MU5N-QNN7. This is a point that Asaf Lubin often makes in discussing his work on regulating the uses of data.
• Id.
• See Corn & Jensen, supra note 11.
• See, e.g., Maddie Gannon, National security adviser says AI is ‘single most dramatic development’ in a long time in exit interview, Spectrum News (Jan. 13, 2025), https://perma.cc/JBA9-3SL5.
• See Galit A. Sarfaty, Corporate Data Responsibility, in Big Data and Armed Conflict, supra note 2, at 275.
• Seeid.
• Seeid.
• See Beth Van Schaack, Leveraging Big Data for LOAC Enforcement: Finding the Needle in a Stack of Needles, in Big Data and Armed Conflict, supra note 2, at 291.
• Seeid.
• Protocol Additional to the Geneva Conventions of 12 August 1949, and Relating to the Protection of Victims of International Armed Conflicts, arts. 51(2), 52(1), June 8, 1977, 1125 U.N.T.S. 3 [hereinafter Protocol I].
• Additional Protocol I, supra note 30, arts. 51(5)(b), 57(2)(a)(iii).
• Additional Protocol I, supra note 30, art. 57(2). For a useful analysis of these principles as applied to attacks on data, see Michael N. Schmitt, Big Data:International Law Issues During Armed Conflict, in Big Data and Armed Conflict, supra note 2., at 151.
• Additional Protocol I, supra note 30, art. 49.
• See Schmitt, supra note 32.
• The example involving the destruction of military data necessary to the operation of Ukrainian weapons is also a hard case. If the operation actually disables the weapons, then some states and experts who view kinetic effects as a prerequisite for an attack may view this as a kinetic effect. But if they interpret kinetic effect as requiring some sort of physical harm to persons or objects of attack, they may view even this sort of operation as falling outside the definition of an “attack.”
• See Schmitt supra note 32.
• See Marco Sassoli & Laura M. Olson, The Relationship Between Human Rights and Humanitarian Law Where It Matters: Admissible Killing and Internment of Fighters in Non-International Armed Conflicts, 90 Int’l Rev. Red Cross 599, 603 (2008); see also Michael N. Schmitt, Big Data:International Law Issues Below the Armed Conflict Threshold, in Big Data and Armed Conflict, supra note 2, at 29.
• See Van Schaack, supra note 28.
• Seeid.
• See Sarfaty, supra note 25.
• Convention (IV) Relative to the Protection of Civilian Persons in Time of War, art. 146, Aug. 12, 1949, 6 U.S.T. 3516.
• See Van Schaack, supra note 28.
• Seeid.
• See Lubin, supra note 8.
• See, e.g., Shiri Krebs, Above the law: Drones, aerial vision and the law of armed conflict—a socio-technical approach, 105 Int’l Rev. Red Cross 1690 (2023).
• See Dickinson, supra note 7.
• See Lubin, supra note 8.
• See Corn & Jensen, supra note 11.
• See, e.g., International Covenant on Civil and Political Rights art. 17, Dec. 19, 1966, 999 U.N.T.S. 171 [hereinafter ICCPR].
• See, e.g., id. at art. 2.
• See Schmitt, supra note 32.
• Seeid.; see also Operational Law Handbook 40 (Marie Anderson & Emily Zukauskas eds., 2008).
• See, e.g., Gary E. Marchant, The Growing Gap Between Emerging Technologies and the Law, in The Growing Gap Between Emerging Technologies and Legal-Ethical Oversight: The Pacing Problem 19 (Gary E. Marchant et al. eds., 2011).
• See, e.g., Kenneth N. Waltz, Theory of International Politics (1979); Hans J. Morgenthau, Politics Among Nations: The Struggle for Power and Peace 5 (5th ed., 1973).
• See, e.g., David M. Kennedy, The Dark Sides of Virtue: Reassessing International Humanitarianism (2005).
• See, e.g., Martha Finnemore, National Interests in International Society (1996); Ryan Goodman & Derek Jinks, Socializing States: Promoting Human Rights through International Law (2013).
• Robert W. Gordon, Critical Legal Histories, in Taming the Past: Essays on Law in History and History in Law 220, 267 (2017).
• Seegenerally Samuel Moyn, Humane: How the United States Abandoned Peace and Reinvented War (2021).
• See Laura A. Dickinson, The Jus in Bello Under Strain: Diluted but not Disintegrating, inIs the International Legal Order Unraveling? 184 (David Sloss ed., 2022).
• See, e.g., Jack L. Goldsmith, Curtis Bradley, and Oona Hathaway, The Failed Transparency Regime for Executive Agreements: An Empirical and Normative Analysis, 134 Harv. L. Rev. 629, 629–30 (2020).
• For further discussion of this point, see Dickinson, supra note 59, at 184.
• Additional Protocol I, supra note 30, art. 49.
• See Schmitt, supra note 32.
• Seeid.
• Seeid.
• See Delerue, supra note 14.
• See Lubin, supra note 8.
• See Ido Kilovaty, Attacking Big Data as a Use of Force, inBig Data and Armed Conflict, in Big Data and Armed Conflict, supra note 2, at 135.
• See, e.g., White Paper on the Need to Strengthen International Humanitarian Law to Address the Challenges of 21st Century Warfare, 57 J. Intl. L. Symp. (forthcoming 2025), https://perma.cc/S4BL-BC7Z.
• See Aoláin, supra note 10.
• Seeid.
• See Schmitt, supra note 32.
• See Sarfaty, supra note 25.
• Seeid.
• See Schmitt, supra note Error! Bookmark not defined..
• See Corn & Jensen, supra note 11.
• Seeid.
• See Dickinson, supra note 59.
• For an example of such an approach in the context of private military and security contractors, see Laura A. Dickinson, Regulating the Privatized Security Industry: The Promise of Public/Private Governance, 63 Emory L.J. 417 (2013).

The temporal boundaries of the international rules governing military force are myopic. By focusing only on the initiation and conduct of war, the legal dichotomy between Jus Ad Bellum and Jus In Bello fails to address the critical role of peacetime military preparations in shaping future conflicts. Disruptive military technologies, such as artificial intelligence and cyber offensive capabilities, only further underscore this deficiency. During their pre-war development, these technologies embed countless design choices, hardcoding into their software and user interfaces policy rationales, legal interpretations, and value judgments. Once deployed in battle, these choices have the potential to precondition warfighters and set in motion violations of international humanitarian law.

This Article highlights glaring inadequacies in how the U.N. Charter, international humanitarian law, and international criminal law currently regulate peacetime military preparations, particularly those involving disruptive technologies. The Article juxtaposes these normative gaps with a growing literature in moral philosophy and theology advocating for Jus Ante Bellum (just preparation for war) as a new limb in the Just War Theory model. By reimagining international law’s temporalities, Jus Ante Bellum offers a proactive framework for addressing the risks posed by the development of disruptive military technologies. Without this recalibration, international law will continue to cede regulatory authority to the silent decisions made in the server farms of defense contractors and the fortified war rooms of central command, where algorithms and military strategies converge to dictate the contours of conflict long before it even begins.

A number of emerging technologies increasingly prevalent on contemporary battlefields—notably unmanned autonomous systems (UAS) and various military applications of artificial intelligence (AI)—are working a sea change in the way that wars are fought. These technological developments also carry major implications for the investigation and prosecution of serious crimes committed in armed conflict, including for an under-examined yet potentially valuable form of evidence: information and material collected or obtained by military forces themselves.

Such “battlefield evidence” poses various legal and practical challenges. Yet it can play an important role in justice and accountability processes, in which it addresses the longstanding obstacle of law enforcement actors’ inability to access the conflict-torn crime scenes. Indeed, military-collected information and material has been critical to prosecutions of international crimes and terrorism offenses in recent years.

The present Article briefly surveys the historical record of battlefield evidence’s use. It demonstrates that previous technological advances—including in remote sensing, communications interception, biometrics, and digital data storage and analysis—not only enlarged and diversified the broader pool of military data but also had similar downstream effects on the (far) smaller subset of information shared and used for law enforcement purposes.

The Article then examines how current evolutions in the means and methods of warfare impact the utility of this increasingly prominent evidentiary tool. Ultimately, it is argued that the technical features of UAS and military AI give rise to significant, although qualified, opportunities for collection and exploitation of battlefield evidence. At the same time, these technologies and their broader impacts on the conduct of warfare risk inhibiting the sharing of such information and complicating its courtroom use.

I. Introduction

I. Introduction