Non-Cruelty to Animals: A General Principle of (Animal) Law

Abstract

Keywords

Non-cruelty to animals, General Principle of Law, International Court of Justice (ICJ), ethical and legal treatment of animals, animal welfare

Suggested Citation Style

Brels, Sabine (2025). Non-Cruelty to Animals: A General Principle of (Animal) Law. Journal of Animal Law, Ethics and One Health (LEOH), 100-110. DOI: 10.58590/leoh.2025.009

* Sabine Brels, International Animal Lawyer, Founder of World Animal Justice (https://worldanimaljustice.org/)

Content

• I. Introduction
• II. Definition of the Principle of Non-Cruelty to Animals
• 1. Scope and Meaning of this Principle
• 2. Replacing 'Unnecessary' with 'Avoidable' Suffering?
• 3. Questioning the Scope of Animal Anti-Cruelty Laws
• 4. The Universal Rejection of Animal Cruelty
• III. The Value of General Principles of Law under Article 38(1) of the ICJ Statute
• 1. Full Definition and Value
• a) International Conventions
• b) International Custom
• c) General Principles of Law
• d) Judicial Decisions and Teachings of Highly Qualified Publicists
• 2. Comprehensive and Dynamic Approach to International Law
• 3. Examples of Recognized General Principles
• 4. Emerging General Principles of Law
• IV. Recognizing Non-Cruelty as a General Principle of Law
• 1. Ethical and General Legal Basis
• 2. Prerequisites for Recognition Under Article 38(1)(c)
• 3. The ICJ's Role and Authority
• 4. Addressing Challenges in Recognition
• V. Judicial and Extra-Judicial Processes to Recognize Non-Cruelty as a New Principle
• 1. The Traditional Judicial Process: The Role of International Litigation in Advancing Non-Cruelty as a General Principle
• 2. The Extra-Judicial Process: The Role of International Instruments for New Principles
• VI. Conclusion

I. Introduction

The principle of non-cruelty towards animals necessitates heightened attention as the global community progresses towards more comprehensive animal protection. This paper advocates for the recognition of the principle of non-cruelty as a General Principle of Law under Article 38(1)(c) of the Statute of the International Court of Justice (ICJ; for the statute, see https://www.icj-cij.org/statute). It understands this principle as generally condemning the unnecessary infliction of suffering on animals, reflecting a common ground in many legal systems. Since the first anti-cruelty law passed in the UK more than two centuries ago (1822, the so-called ‘Martins Act’), anti-cruelty laws have spread worldwide, and this principle is now embedded in the legal frameworks of a significant majority (more than two-third) of the world's nations (Brels, 2017).

Source: World Animal Justice©, 2024, online: https://worldanimaljustice.org/

This paper argues that this principle holds international legal value and should be recognized by the ICJ, with substantial implications for global animal welfare laws.

II. Definition of the Principle of Non-Cruelty to Animals

This section defines the principle of non-cruelty, discusses its ethical and legal basis, and proposes a more objective interpretation of its core terminology.

1. Scope and Meaning of this Principle

The principle of non-cruelty towards animals, as described by legal scholars such as Harrison (2015) and Beirne (2012), refers to a normative standard prohibiting the ‘unnecessary infliction of suffering on sentient animals’. This principle aligns with the ethical view that causing undue harm to sentient beings is inherently wrong. It encompasses various forms of cruelty, including physical abuse, neglect, and practices that cause significant psychological distress to animals (Beirne, 2012). However, it is important to note that ‘zoophilia’ is prohibited in the vast majority of countries, but a few still do not explicitly ban this inhumane practice.

2. Replacing 'Unnecessary' with 'Avoidable' Suffering?

While the principle of non-cruelty towards animals condemns the ‘unnecessary infliction of suffering’, the term ‘unnecessary’ is inherently subjective and open to varying interpretations by different judges in different jurisdictions. Many eminent animal law scholars, such as Gary L. Francione or Steven M. Wise (e.g., Francione, 1995) argue that what is deemed ‘necessary’ can be influenced by cultural, economic, and social factors, leading to inconsistent applications of anti-cruelty laws.

For instance, in France, forced-feeding ducks and geese for foie gras is considered necessary to preserve a ‘gastronomical tradition’, despite foie gras not being essential and even bad for nutritional purpose. This practice contrasts sharply with the widespread jurisdictions, such as, for example, Switzerland, where such force-feeding is deemed inhumane and unnecessary.

To address this subjectivity, we propose interpreting the term ‘unnecessary’ through the lens of what is reasonably ‘avoidable’ in animal protection laws. Under such an interpretation, any form of animal suffering that could reasonably be avoided should not be permitted. This approach has the potential to ban cruel traditions and practices and to support the development and adoption of alternatives that avoid suffering and save animal lives.

When confronted with this interpretative shift, judges would no longer ask whether the infliction of animal suffering is necessary for human interests such as economic gain or cultural traditions. Rather, the guiding question would become: is the suffering objectively avoidable? This change could significantly benefit animals and align with a more moral and humane civilization. While we acknowledge that both terms are contextually influenced, 'avoidable' provides a practical ethical benchmark grounded in precaution and evolving standards of necessity.

For example, plant-based proteins can replace meat, offering a more ethical, ecological, and healthy alternative. Growing plant proteins uses less water and food, reduces antibiotic resistance and pollution, and avoids the health risks associated with saturated fats and zoonotic diseases (see, e.g., Viroli et al., 2023). Factory farming, characterized by intensive confinement and inhumane conditions, is a significant contributor to disease outbreaks and often falls short of even basic animal welfare objectives, despite existing regulations. Promoting alternatives – such as plant proteins – can help prevent avoidable animal suffering while also improving overall human and environmental health.

Interpreting ‘unnecessary’ as ‘avoidable’ helps thus promote a clearer, more consistent standard for animal welfare, emphasizing the importance of preventing all forms of avoidable animal suffering and fostering a more humane and sustainable world.

3. Questioning the Scope of Animal Anti-Cruelty Laws

Many anti-cruelty laws include provisions that prohibit actions causing unnecessary suffering to animals, particularly vertebrates and companion animals, thereby excluding a vast number of invertebrate species. Therefore, these laws cover only a small percentage of animals. In fact, a 2024 World Animal Justice comparative study showed that many animals are excluded from general anti-cruelty laws. Moreover, animal protection laws often apply only to companion animals with owners, leaving stray and feral animals unprotected. Wild animals are usually subjected to specific regulations, particularly when they are classified as endangered species or subject to specific rules governing trapping or hunting methods. Farm and laboratory animals are likewise often covered by distinct legal regimes, as are other human activities involving animals for sport and entertainment.

Furthermore, anti-cruelty laws often contain exemptions that reduce their scope of protection even more. For instance, in France, bullfighting is allowed in the south of France, and cockfighting in the north and on French islands for ‘traditional’ purposes (art.521-1 Penal Code). In the US, the federal Humane Methods of Slaughter Act (HMSA), which is the primary law regulating the humane treatment of farm animals at slaughter, explicitly excludes chickens and other poultry, who are massively exploited. Indeed, the federal Humane Methods of Slaughter Act (HMSA) requires that animals be rendered insensible to pain before being slaughtered, but it only applies to cattle, pigs, sheep, and goats, leaving chickens, turkeys, and other birds unprotected under this act. Yet, chickens are the most widely farmed and consumed animals in the United States, with billions raised and slaughtered each year. The exclusion of chickens and other poultry from the HMSA means that these animals are not afforded the same legal protections for humane treatment during slaughter as other farm animals. This has been a significant concern for animal welfare advocates, who argue for the extension of humane slaughter regulations to include all species of farm animals.

Similarly, the U.S. federal law (the US Animal Welfare Act, AWA) on animal experimentation excludes animal species like rats and mice, and birds, which are the most commonly used animals in laboratory research, despite the fact that these species constitute the vast majority of animals used in research, numbering in the millions each year. Estimates suggest that these excluded species make up about 95% of the animals used in research (see, e.g. Animal Legal Defense Fund, n.d.). Therefore, the AWA effectively protects only about 5% of laboratory animals, leaving most animal individuals without legal protections. This discrepancy has been a point of contention among animal rights advocates, who argue for broader protection under the law.

4. The Universal Rejection of Animal Cruelty

The widespread incorporation of anti-cruelty statutes in diverse legal systems – from common law to civil law traditions – demonstrates a broad consensus on the importance of protecting animals from cruelty (Harrison, 2015).

A fundamental principle is shared by many societies: animal cruelty should be avoided and prevented. However, while the principle of non-cruelty enjoys wide support, interpretations of cruelty may vary across cultures, leading to different interpretations of what qualifies as animal cruelty and differing levels of support for certain practices involving animals. Notwithstanding this, we note a progressive development of animal welfare laws at national, regional, international, and United Nations levels. However, many anti-cruelty laws contain exemptions, which suggests that states do not treat non-cruelty as an absolute principle. Furthermore, anti-cruelty laws are often only being implemented leniently and inconsistently. However, ICJ precedent suggests that for a principle to be considered a General Principle of Law, it must be truly universal across legal systems.

III. The Value of General Principles of Law under Article 38(1) of the ICJ Statute

This section explains the legal relevance of General Principles of Law within international law and how they fill legal gaps in the ICJ context.

1. Full Definition and Value

Article 38(1) of the Statute of the International Court of Justice (ICJ) outlines the sources of international law that the Court applies when adjudicating disputes in these words:

“The Court, whose function is to decide in accordance with international law such disputes as are submitted to it, shall apply: a. international conventions, whether general or particular, establishing rules expressly recognized by the contesting states; b. international custom, as evidence of a general practice accepted as law; c. the general principles of law recognized by civilized nations; d. subject to the provisions of Article 59, judicial decisions and the teachings of the most highly qualified publicists of the various nations, as subsidiary means for the determination of rules of law.”

a) International Conventions

These are formal agreements between states that establish specific legal rules and obligations. They reflect the explicit consent of the parties involved and create binding standards for the conduct of states (ICJ-Statute, 1945). For example, the Convention on International Trade in Endangered Species (CITES) establishes rules for the protection of overexploited wildlife species through international cooperation.

b) International Custom

International custom consists of practices that have evolved over time and are accepted as binding law by the international community. These customs are recognized due to their widespread and consistent application, coupled with a belief in their legal obligation (ICJ-Statute, 1945). An example is the prohibition of torture, which is recognized as a customary international law principle.

c) General Principles of Law

These are fundamental legal norms recognized across diverse legal systems and serve as a basis for judicial decisions in the absence of specific treaties or customs. General principles include well-established concepts such as pacta sunt servanda (agreements must be kept) and res judicata (a final judgment is conclusive) (ICJ-Statute, 1945). They serve as a foundation for resolving disputes by filling gaps in international law.

d) Judicial Decisions and Teachings of Highly Qualified Publicists

Article 38(1)(d) broadens the sources of international law to include judicial decisions and the writings of the most qualified scholars. While judicial decisions do not constitute binding precedent, they offer valuable insights into the application and interpretation of international law. Scholarly writings, meanwhile, contribute to the development and understanding of legal principles by offering expert analysis and interpretations (ICJ Statute, 1945). This provision enables the ICJ to engage with the evolving discourse on legal issues and to draw on well-reasoned arguments from distinguished scholars in shaping its judgments.

2. Comprehensive and Dynamic Approach to International Law

The inclusion of Article 38(1)(d) underscores the ICJ's commitment to a comprehensive and dynamic approach to international law. While international conventions, customs, and general principles form the primary sources of law, the Court's consideration of judicial decisions and scholarly teaching ensures that evolving legal thought and practical interpretations are also taken into account. This approach acknowledges the importance of both formal legal sources and the scholarly contributions in shaping and refining international legal norms. It enables the ICJ to respond to new developments and to address complex legal issues not fully covered by existing treaties or customs.

In the context of recognizing the principle of non-cruelty towards animals, Article 38(1)(d) offers a valuable avenue for incorporating emerging legal concepts and scholarly perspectives into international law. Although the principle of non-cruelty has not yet been codified as a general principle under international law, it is increasingly reflected in evolving judicial decisions and academic discourse that signal a growing global consensus on the importance of animal welfare. By drawing on these subsidiary means, the ICJ has the potential to support the development of a more comprehensive and inclusive legal framework that addresses the protection of animals against cruelty.

3. Examples of Recognized General Principles

Several general principles of law have been recognized by the ICJ, demonstrating the application of this source of international law:

• Pacta sunt servanda: The principle that agreements must be kept, ensuring that treaties are honored (ICJ, 1951).
• Res judicata: The principle that a final judgment by a competent court is conclusive between the parties involved (ICJ, 1966).
• Bona fides: The principle of good faith in the performance of legal obligations (ICJ, 1986).

These classical principles illustrate how the ICJ has applied general principles to ensure fairness and consistency in international legal proceedings. However, general principles of law are not limited to these traditional principles.

4. Emerging General Principles of Law

Recent developments in international law have introduced new general principles, reflecting evolving global norms and values. These include:

• Non-Intervention: The principle that states should not interfere in the internal affairs of other states (ICJ, 1965).
• Prohibition of the Use of Force: The principle that the use of force is prohibited except in self-defense or with Security Council authorization (UN Charter, 1945).
• Prohibition of Abuse of Rights: The principle that rights must be exercised in good faith and not to the detriment of others (ICJ, 1986).

It is worth considering whether the principle of prohibition of abuse of rights could be extended to the field of animal protection. If recognized in this context, it would prohibit the exercise of individual and proprietary rights in ways that cause avoidable harm to animals. Such an application aligns with the notion that rights and freedoms should be exercised responsibly, including in the context of animal welfare (Boone, 2020).

IV. Recognizing Non-Cruelty as a General Principle of Law

This section builds the case for recognizing non-cruelty as a General Principle of Law based on ethical imperatives, legal precedent, and practical criteria under Article 38(1)(c).

1. Ethical and General Legal Basis

Ethically, the principle of non-cruelty is grounded in the recognition of animals as sentient beings capable of experiencing pain and suffering (Singer, 1995). Legally, it is reflected in the statutes and judicial decisions of numerous countries that condemn cruel practices and mandate humane treatment (Regan, 2004). The ethical and legal foundations of the principle of non-cruelty provide a compelling case for its recognition as a General Principle of Law.

However, before the ICJ can recognize a General Principle of Law under Article 38(1)(c), it must be shown that the principle is widely accepted across major legal systems, applied with a reasonable degree of consistency, and regarded as fundamental to the notion of justice. This recognition often builds on national laws, regional agreements, and scholarly affirmation.

2. Prerequisites for Recognition Under Article 38(1)(c)

The International Court of Justice (ICJ) may recognize a new General Principle of Law (GPL) under Article 38(1)(c) of its Statute, provided that several prerequisites are met (Pellet, 2006).

• First, the principle must be recognized across the major legal systems of the world.
  The principle of non-cruelty to animals is currently enshrined in the domestic legislation of over two-thirds of the sovereign States. This widespread adoption in both civil and common law jurisdictions, including numerous developing nations, confirms the principle's broad acceptance. While interpretations may vary, the foundational condemnation of cruelty is a shared legal norm.
• Second, the principle must be sufficiently general and fundamental, serving as a normative anchor across varied contexts. Non-cruelty fulfills this requirement by expressing a core ethical and legal tenet: that the infliction of suffering on sentient beings, when avoidable, is morally and legally reprehensible. This core idea transcends cultural or sectoral specificities.
• Third, the principle must serve the needs of international adjudication by helping avoid non liquet – instances where the Court lacks applicable legal rules. As this paper demonstrates, the lack of a clear international legal standard prohibiting animal cruelty often impedes the pursuit of justice in cases of cross-border animal abuses or violations arising in international contexts, such as international trade or environmental harm. The recognition of a general principle would help fill these legal lacunae and provide greater clarity for adjudication.
• Fourth, the principle must be consistently reflected in national jurisprudence and doctrine. Numerous jurisdictions already apply anti-cruelty norms in Court, and leading scholars across legal systems – particularly in international environmental and animal law – have affirmed the foundational value of the principle of non-cruelty. These doctrinal affirmations complement judicial enforcement and scholarly consensus.
• Fifth, the principle must not encounter prevailing opposition from the world’s major legal traditions. While cultural and economic objections remain – such as those linked to certain cruel traditional practices or factory farming – these do not amount to a fundamental legal rejection of non-cruelty but instead reflect policy carve-outs or transitional challenges. There is no active legal denial of the legal core norm (i.e., the cruelty principle); rather, the debate centers on its scope (namely, which animals, activities, and practices fall within its protection), but not its core validity.

Taken together, these conditions make the recognition of non-cruelty as a General Principle of Law not only possible, but necessary. It reflects an emerging global standard, provides a much-needed legal benchmark in international law, and aligns with broader ethical imperatives.

3. The ICJ's Role and Authority

The ICJ, as the principal judicial organ of the United Nations, is empowered to recognize general principles of law under Article 38(1)(c) of its Statute.

Given the broad global acceptance of anti-cruelty norms, the ICJ can – and arguably should – acknowledge the principle of non-cruelty as a General Principle of Law. Such recognition would align with the Court's mandate to reflect the common values and legal standards shared by the international community (ICJ Statute, 1945).

Resistance to recognizing non-cruelty as a General Principle of Law may arise from concerns about interference with cultural traditions, economic interests, or differing ethical frameworks. Such objections should be addressed through diplomatic engagement, education, and gradual legal adaptation.

4. Addressing Challenges in Recognition

Although General Principles of Law are not easily recognized by the ICJ, the recognition of the principle of non-cruelty would be both logical and desirable from a legal and moral standpoint. Such recognition would ensure minimal protection of animals against cruelty, particularly in jurisdictions where no legal basis currently exists to protect them. The principle of non-cruelty thus provides a foundational legal and moral guideline that can be universally applied (Boone, 2020). Arguably, it does face several potential challenges from states, primarily on political, cultural, legal, and economic grounds.

However, recognizing the principle of non-cruelty as a General Principle of Law would promote greater harmony between international and national legal frameworks, even if this process unfolds gradually over time. Such harmonization could facilitate the development of more comprehensive international treaties and conventions aimed at protecting animals from cruelty. It would also encourage states to align their domestic legislation with an internationally recognized standard, thereby fostering greater consistency in animal welfare protection (Ryder, 2000).

V. Judicial and Extra-Judicial Processes to Recognize Non-Cruelty as a New Principle

This section analyzes the judicial and extra-judicial pathways for integrating the principle of non-cruelty to animals into international law.

1. The Traditional Judicial Process: The Role of International Litigation in Advancing Non-Cruelty as a General Principle

Traditionally, the judicial function in international law involves identifying General Principles of Law to avoid non-liquet (a denial of justice) in the absence of a specific international rule. In the context of animal welfare protection, the ICJ could play a pivotal role by laying the groundwork for recognizing animal protection as a General Principle of Law. The ICJ's decision in the Whaling in the Antarctic case (Australia v. Japan: New Zealand intervening, 2014) demonstrates its capacity to address new issues and could be viewed as a precedent for recognizing animal protection as part of the ‘legal conscience of civilized nations’.

The case for recognizing non-cruelty to animals as a General Principle of Law is further supported by key international precedents that have already acknowledged the importance of animal protection. International litigation has played a transformative role in the evolution of international animal law. Two notable legal milestones illustrate this trajectory: the recognition of animal welfare as a legitimate concern under the World Trade Organization (WTO) law and the condemnation of commercial whaling by the ICJ in Whaling in the Antarctic.

In 2013, the Judicial Body of the WTO recognized animal welfare as a 'public moral' concern under Article XX(a) of the GATT in the European Communities – Seal Products case. The EU Seal Regime, which prohibited the importation and marketing of seal products derived from inhumane hunts, was upheld by the WTO as a legitimate trade restriction, despite certain exemptions being ruled as inconsistent. The decision affirmed that the moral concern for animal welfare constitutes a valid legal basis for imposing trade restrictions under international law.

At the ICJ level, the 2014 case Whaling in the Antarctic, marked a significant development in the intersection of animal protection and international law. In this case, the ICJ ruled that Japan’s JARPA II program violated the International Convention for the Regulation of Whaling. The Court concluded that the lethal whaling conducted under the guise of scientific research lacked scientific merit and was primarily commercial in nature. The ICJ’s ruling required Japan to cease its activities, and this marked the first time the Court upheld international obligations rooted in animal protection and environmental integrity.

Together, these landmark decisions illustrate that animal protection can be elevated to the international legal level and that courts are increasingly willing to recognize the legitimacy and importance of animal welfare. These precedents provide a compelling foundation for the ICJ to recognize non-cruelty as a General Principle of Law in a future case.

2. The Extra-Judicial Process: The Role of International Instruments for New Principles

An extra-judicial process to recognizing a principle may occur through formal international instruments like a Multilateral Treaty or a Convention Framework (Danilenko, 1993). If animal protection were recognized as a General Principle of Law in a future treaty, it could then become a general principle of international law. A global instrument, such as a United Nations (UN) framework convention on animal protection, that expressly condemns preventable cruelty and mistreatments of animals, could significantly advance the recognition of this principle and fill the current gap to protect animals as sentient beings in a binding international law agreement (Brels, 2017).

There is a promising precedent for this approach. On 2 March 2022, the United Nations Environment Assembly (UNEA) adopted the UN Nexus Resolution, which explicitly acknowledges the importance of animal welfare within the broader context of environmental protection, sustainable development, and the One Health framework. This resolution sets a significant precedent for the integration of animal welfare into global environmental governance. It also creates a pathway toward the eventual adoption of a more comprehensive international instrument that explicitly addresses animal protection. By aligning animal welfare with environmental and human health concerns, this resolution offers both a legal and political foundation for future global agreements that combat cruelty and advance animal welfare in international law.

VI. Conclusion

In conclusion, the principle of non-cruelty towards animals, widely recognized and embedded in the national legal systems around the world, clearly meets the criteria for recognition of a General Principle of Law under Article 38(1)(c) of the Statute of the International Court of Justice. This paper has argued that the ICJ should formally recognize this principle, given its robust legal and ethical foundations and the far-reaching implications for global animal welfare. Such recognition would mark a significant step towards a more humane and just international legal framework – one that affirms a consistent and universal standard against cruelty and strengthens global protection for animals.

By advancing the principle of non-cruelty as a General Principle of Law, the international community affirms its collective responsibility to protect animals and to unequivocally condemn and address cruelty to animals. Recognition of this principle by the ICJ would demonstrate a profound commitment to safeguarding the dignity and well-being of all sentient beings, while establishing a foundational legal standard in areas where binding protection remains absent.

While the recognition of non-cruelty as a General Principle of Law may remain contested within the international legal community, this paper has demonstrated that the principle of non-cruelty constitutes already a general principle of animal law. Acknowledging it as such could serve as a steppingstone towards the development of a dedicated international instrument that specifically condemns animal cruelty on a global scale.

Such an instrument is currently absent from the framework of international law. Recognizing non-cruelty as a general principle would pave the way for its development. In this context, the role of the ICJ in adopting a broad and progressive interpretation of Article 38(1)(c) is crucial. By doing so, the Court can contribute to a broader understanding and acknowledgment of animal rights and protection within international law, reinforcing evolving norms and ethical standards that prioritize humane treatment and protection of animals. Ultimately, this would support a more unified and robust global stance against animal cruelty, ensuring it is not only universally condemned, but also effectively prevented and penalized.

Copyright (c) 2025 Sabine Brels

This work is licensed under a Creative Commons Attribution-NoDerivatives 4.0 International License.