Column Foreign Affairs and National Security 2025.10.29
Urgently Advocating a Precise Understanding of the Principle of Proportionality: From the Perspective of the Inherent Situation of the Japan Coast Guard and the Japan Maritime Self-Defence Force
Regulations and Legal Systems
This paper is an expanded version in English of the paper by the same author which was published at the HP of the Canon Institute for Global Studies (CIGS) on the 22nd of September, 2025. As well as the previous one, it is also the work of the author as a member of “Compass Voice-External Expert Network of the Japan Coast Guard.” The two papers share the common purpose as the lead to the previous one explains. The gist is as follows:
“The author has repeatedly heard the misconception that the principle of proportionality means ‘it is permissible to respond with the same actions as the adversary.’ This is entirely erroneous. As will be clarified in this paper, it is an extremely grave and dangerous misunderstanding for the safety of not only the Japan Coast Guard (JCG) but also the Japan Maritime Self Defence Force (JMSDF). When the JMSDF conducts maritime ‘police’ operations under Article 82 of the Self-Defence Forces Law, the same restrictions on its use of weapons apply as for the JCG. As Japanese domestic law, Article 7 of the Police Duties Execution Act provides for the restrictions on the use of weapons accompanying law enforcement measures. Article 7 provides for the so-called ‘police proportionality’, and the use of weapons causing harms is subject to more restrictive limitation. The ‘police proportionality’ is totally difference from ‘principle of proportionality’ in the law of armed conflict of international law.
As an international law scholar, the author wishes to resolve these misunderstandings surrounding proportionality by providing theoretical clarification and the dissemination of knowledge.
However, this is not the sole purpose of this paper. It is a brief paper addressing a more serious and urgent issue. The author's grave concern is that without accurate recognition and understanding of the law—specifically, the principle of proportionality—the safety of the JCG and also the JMSDF will be significantly threatened.
Based on these concerns, providing help in accurately recognizing and understanding proportionality is a critical and urgent task for the author. Addressing this task is the purpose of this paper.”
The author wrote the paper in English, which is now being published, with bearing the basic ideas as follows.
First, it is useful and significant to analyze the principle of proportionality in the actual context of practice. Second, it is necessary for the author, a Japanese, to issue this paper in English with explanation of the inherent characteristics of the Japan Coast Guard from a comparative perspective of international practice regarding the relationship between military organs and coast guards.
The second point was explained when the author issued at the HP of CIGS her presentation for the Malaysia Maritime Security Conference 2025 which was held on the 21st of May 2025, in Malaysia. The gist is as follows:
“The inherent point of the relationship between the Japan Maritime Self-Defence Force and the Japan Coast Guard is the latter’s strict adherence to its nature as a policy/ law enforcement organ. Even in the extreme occasions of responding to armed attacks and coping with armed conflicts, the Japan Coast Guard would operate as a police/law enforcement organ in conjunction with the Japan Maritime Self-Defence Force.
The most important result by this is the strict limitation on the use of weapons by the Japan Coast Guard.
In many countries of the world, coast guards and navies, on such extreme occasions of armed attacks and armed conflicts, would work together, in some sense, by incorporating the former into the latter. Roughly speaking, coast guards are allowed to work as military/ self-defence organs on such limited occasions.
So, the special relationship between the Japan Maritime Self-Defence Force and the Japan Coast Guard should be difficult for other countries to understand.
Nonetheless, I think it is my responsibility, as a Japanese participant, to take the opportunity of the Conference, to explain to and ask enough understanding of, every stakeholder of the friendly counties, regarding the special relationship between the Japan Maritime Self-Defence Forces and the Japan Coast Guard. This is because, they have the possibility to cooperate with Japan to recover and maintain the peace and security responding to armed attacks and coping with armed conflicts in neighbouring sea areas.”
[The related works by Research Director Atsuko Kanehara]
- “Indispensable Understanding of the Principle of Proportionality for Securing the Safety of the Japan Coast Guard (in Japanese)”
- “Research Director Atsuko Kanehara participated in the Malaysia Maritime Security Conference 2025, which was held on the 21st of May 2025, in Malaysia. ”
- “How to Ensure the Safety of the Japan Coast Guard While Maintaining Its Nature as a Police Organ When It Conducts Missions in Collaboration with the Japan Maritime Self-Defense Force under the Control Guidelines,”
- Japan Review, Vol. 6, Nov. 2, https://www.jiia-jic.jp/en/japanreview/pdf/05JapanReview_Vol6_No2_Atsuko%20Kanehara.pdf
- “Reconsideration of the Distinction between the Use of Arms in Law Enforcement and the Use of Force Prohibited by International Law―With an Analysis of the Inherent Significance of This Issue to Japan,” Japan Review, Vol. 5, No. 2, https://www.jiia-jic.jp/en/japanreview/pdf/JapanReview_Vol5_02_%20Kanehara.pdf
- “The Use of Force in Maritime Security and the Use of Arms in Law Enforcement under the Current Wide Understanding of Maritime Security,” Japan Review, Vol. 3, No. 2,
Research Director Kanehara is Member of Compass Voice - External Expert Network of the Japan Coast Guard