The Legality of Espionage in Peacetime
Summary: 1. Introduction. – 2. Research Methodology. – 3. Legality of Espionage in Light of the Principle of State Sovereignty. – 3.1 Indirect Prohibition under the Principle of Non-intervention. – 3.1.1 Limits of the Principle of Non-Intervention. – 3.1.2 Impact of Espionage on the Principle of Non-Intervention. – 3.2 Indirect Prohibition in the light of the conventional rules. – 3.2.1 Impact of Espionage on the Maritime Sovereignty. – 3.2.2 Impact of Espionage on the Aerial Sovereignty. – 3.2.3 Impact of Espionage on Diplomatic Relations. – 4. Legality of Espionage in Light of the Human Rights Law. – 4.1 Mass Surveillance and Bulk Data Collection and Privacy Interference. – 4.2 Balancing Espionage and Privacy Right: The Necessity and Proportionality Test. – 5. Legality of espionage in Light of Customary International Law 6. Conclusions
Background: This research paper examines the legality of espionage during peacetime under the rules of international law. To address this issue, the paper focuses on several relevant international law rules, including the obligation to respect the sovereignty of other states and the prohibition on intervention. Although espionage is a longstanding instrument of statecraft essential for safeguarding national security, it occupies an uncertain legal position. International legal frameworks, including the UN Charter and customary international law, establish obligations such as the respect for state sovereignty and the prohibition of intervention, which espionage activities frequently challenge. The growth of modern surveillance capabilities, especially in the cyber domain, further complicates the legal and ethical boundaries of espionage.
Methods: The study draws upon relevant international rules, such as the UN Charter and customary international law, as well as recent rulings by the International Court of Justice (ICJ) and the European Court of Human Rights (ECtHR), which can serve as a foundation for developing regulatory frameworks for espionage operations and surveillance activities. The study adopts a doctrinal legal research approach by systematically analysing primary sources of international law, including treaties, customary law principles, and jurisprudence from the ICJ and the ECtHR. It also incorporates a comparative review of state practice and relevant academic commentary to assess whether existing legal norms adequately regulate espionage activities during peacetime.
Results and Conclusions: The findings indicate that espionage occupies a legally ambiguous space, particularly concerning the applicability of core principles of non-intervention and state sovereignty—especially in the cyber domain. In parallel, privacy has become enshrined in emerging human rights law, and legal safeguards around state surveillance have been introduced, emphasising proportionality, accountability, and supervision. Still, espionage operates in a highly nuanced legal and ethical territory that is neither wholly abhorrent nor entirely permissible.
This contradiction reflects the ongoing tension between the challenges of balancing national security and the protection of individual rights. While espionage is widely acknowledged as vital to state security, international law does not explicitly ban it despite its potential to violate sovereignty and the principle of non-intervention. However, international law—through its emphasis on territorial integrity and sovereign equality—does not impose certain restraints on espionage activities.
The study concludes that although espionage remains a multifaceted and indispensable component of state actions, it should not violate the principles and laws of sovereignty, human rights, or the broader framework of international law during peacetime. Legal and ethical ambiguity persists, necessitating the development of clearer regulatory frameworks that strike a balance between legitimate intelligence gathering and respect for sovereignty and individual rights. Ultimately, the research underscores that intelligence activities should not be permitted to undermine the stability of the international legal order or erode fundamental human rights protections.
Abstract
Background: This research paper examines the legality of espionage during peacetime under the rules of international law. To address this issue, the paper focuses on several relevant international law rules, including the obligation to respect the sovereignty of other states and the prohibition on intervention. Although espionage is a longstanding instrument of statecraft essential for safeguarding national security, it occupies an uncertain legal position. International legal frameworks, including the UN Charter and customary international law, establish obligations such as the respect for state sovereignty and the prohibition of intervention, which espionage activities frequently challenge. The growth of modern surveillance capabilities, especially in the cyber domain, further complicates the legal and ethical boundaries of espionage.
Methods: The study draws upon relevant international rules, such as the UN Charter and customary international law, as well as recent rulings by the International Court of Justice (ICJ) and the European Court of Human Rights (ECtHR), which can serve as a foundation for developing regulatory frameworks for espionage operations and surveillance activities. The study adopts a doctrinal legal research approach by systematically analysing primary sources of international law, including treaties, customary law principles, and jurisprudence from the ICJ and the ECtHR. It also incorporates a comparative review of state practice and relevant academic commentary to assess whether existing legal norms adequately regulate espionage activities during peacetime.
Results and Conclusions: The findings indicate that espionage occupies a legally ambiguous space, particularly concerning the applicability of core principles of non-intervention and state sovereignty—especially in the cyber domain. In parallel, privacy has become enshrined in emerging human rights law, and legal safeguards around state surveillance have been introduced, emphasising proportionality, accountability, and supervision. Still, espionage operates in a highly nuanced legal and ethical territory that is neither wholly abhorrent nor entirely permissible.
This contradiction reflects the ongoing tension between the challenges of balancing national security and the protection of individual rights. While espionage is widely acknowledged as vital to state security, international law does not explicitly ban it despite its potential to violate sovereignty and the principle of non-intervention. However, international law—through its emphasis on territorial integrity and sovereign equality—does not impose certain restraints on espionage activities.
The study concludes that although espionage remains a multifaceted and indispensable component of state actions, it should not violate the principles and laws of sovereignty, human rights, or the broader framework of international law during peacetime. Legal and ethical ambiguity persists, necessitating the development of clearer regulatory frameworks that strike a balance between legitimate intelligence gathering and respect for sovereignty and individual rights. Ultimately, the research underscores that intelligence activities should not be permitted to undermine the stability of the international legal order or erode fundamental human rights protections.
About Authors
Fawaz Najem*
PhD Researcher in Public Law, University of Sharjah, Sharjah, United Arab of EmiratesU23101493@sharjah.ac.ae
https://orcid.org/0009-0007-5623-8973
Corresponding author, responsible for writing the original draft, the methodology, and the formal analysis.
Abdelnaser Aljahani
Associate Professor of International Law, University of Sharjah, Sharjah, United Arab of Emirates
https://orcid.org/0000-0003-0937-6824
Co-author, responsible for conceptualizing, reviewing, and supervising the original draft.
Competing interests: No competing interests were disclosed.
Disclaimer: The authors declares that their opinion and views expressed in this manuscript are free of any impact of any organizations.
Copyright: © 2025 Fawaz Najem and Abdelnaser Aljahani. This is an open access article distributed under the terms of the Creative Commons Attribution License, (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
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Publication history
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Date of submission: 03 May 2025
Date of acceptance: 22 Jun 2025
Online First publication: 05 Aug 2025
Last Publication: 17 Aug 2025
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Number of revision rounds: 1 round with major revisions
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How to cite it?
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Najem F and Aljahani A, ‘The Legality of Espionage in Peacetime’ (2025) 8(3) Access to
Justice in Eastern Europe 120-51 <https://doi.org/10.33327/AJEE-18-8.3-a000118>
DOI: https://doi.org/10.33327/AJEE-18-8.3-a000118
Managing editor – Mag. Bohdana Zahrebelna. English Editor – Julie Bold.
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