BANZAI, Hiroyuki

Official Title



(School of Law)

Contact Information

Mail Address

Mail Address


Grant-in-aids for Scientific Researcher Number



Faculty of Law(Graduate School of Law)

Faculty of Political Science and Economics(School of Political Science and Economics)

Faculty of Social Sciences(Graduate School of Social Sciences)

Affiliated Institutes


研究所員 2016-


研究所員 2018-2018

Educational background・Degree

Educational background

-2003/03 Waseda University Graduate School, Division of Law Public International Law
-1995 Waseda University Faculty of Laws


Master of Law Coursework Waseda University International law

Doctor of Laws Thesis Waseda University International law


2009/04-2011/03Associate Professor, School of Law, Waseda University
2011/04-Professor, School of Law, Waseda University

Academic Society Joined

Japanese Association of International Law, Japanese Association of World Law, American Society of International Law, EU Studies Association JAPAN

OfficerCareer(Outside the campus)



Adachi Mineichiro Memorial Award

2016/10Conferment Institution:Adachi Memorial Foundation

Title:Study on State Responsibility for Internationally Wrongful Act: Basic Problems of the Theory on State Responsibility

Research Field


Sources of Law, International Responsibility of States, Disarmament and Non-Proliferation of WMD

Grants-in-Aid for Scientific Research classification

Social sciences / law / International law

Research interests Career

2009-2012State Responsibility for Internationally Wrongful Act

Current Research Theme Keywords:State Responsibility, Internationally Wrongful Act

Individual research allowance




早稲田大学大学院法研論集 p.239 - 2651999/03-



早稲田大学大学院法研論集 (94) p.177 - 2042000/06-



早稲田法学会誌 52p.251 - 2942002/03-



駿河台法学 18(1) p.1 - 1382004/09-



石川明編『国際経済法と地域協力(櫻井雅夫先生古稀記念論集)』(信山社、2005年) p.97 - 1312005/02-



駿河台法学 19(2) p.123 - 1722006/02-

Sources of International Law - Toward Positive Participation in the Formation of General International Law-

Hiroyuki BANZAI

Korea International Law Review (27) p.169 - 1872008/04-



島田征夫・古谷修一編『国際法の新展開と課題(林司宣先生古稀祝賀)』 p.3 - 302009/04-



早稲田大学社会安全政策研究所紀要 (2) p.145 - 1682010/03-

The Proliferation Security Initiative and International Law of the Sea: A Japanese Lawyer's Perspective

Journal of East Asia and International Law 3(1) p.7 - 282010/05-



季刊社会安全 (78) p.2 - 62010/10-



早稲田法学 86(2) p.89 - 1302011/03-



早稲田大学法学研究科組織的な大学院教育改革推進プログラム『法学研究の基礎〈法と権利〉』 p.233 - 2532011/03-



早稲田大学社会安全政策研究所紀要 (4) 2012/03-



早稲田法学 88(2) p.65 - 1282013/03-

Function of the Provisions of Responsibility of States in Treaties

Hiroyuki Banzai

(7) p.3 - 202015/08-

Disputes on State Responsibility for the Restoration of a Common Interest in International Law

Hiroyuki BANZAI

Journal of International Law and Diplomacy Peer Review Yes 117(1) p.25 - 482018/05-2018/05


Outline:In this article, the relationship between a responsible state and a state to invoke the responsibility will be examined with reference to breach of obligations under the rules of customary law or treaties, in which the regimes of common interests in international community are established. The “mise en œuvre” of state responsibility has taken a form of “claim for reparation from the injured state to the responsible state”, such as Corfu Channel case (1949) and Case concerning United States Diplomatic and Consular Staff in Tehran (1980), based on the claims for reparation to damages of states caused by internationally wrongful acts. Since that is thought to be a single form of international claims, the exercise of diplomatic protection should be theorized in the same form as the direct injury to state itself. Thus, the customary methods of international claims have been evolved on the premise that the parties of a dispute shall be individualized in order to establish a bilateral legal relationship of state responsibility. According to the International Court of Justice (ICJ), the norms of common interests are the ones that “one cannot speak of individual advantages or disadvantages to States, or of the maintenance of a perfect contractual balance between rights and duties.” In such a norm, the states “do not have any interests of their own; they merely have, one and all, a common interest, namely, the accomplishment of those high purposes which are the raison d'être of the convention” (Reservations to the Convention on the Prevention and Punishment of the Crime of Genocide, I.C.J. Reports 1951, p. 23). In the breach of this type of norms, there may be no specific states that are injured individually. In the merit of South West Africa Case (1966), the applicant states were held to have no locus standi for lack of the material interests of their own under Article 2 of the Mandate and Article 22 of the League Covenant. After this judgement, various efforts have been made to overcome the traditional idea of bilateralism of international claims. A provision of the third state remedy for the restoration of a common interest was drafted in the Articles on Responsibility of States for Internationally Wrongful Acts (2001). This is the famous provision of Article 48. According to the International Law Commission (ILC), however, it includes some elements of progressive development, not existing law. Irrespective of such a hesitation of the ILC, the influence of Article 48 had been strong enough that the ICJ finally has come to affirm locus standi of third states in the case of Questions Relating to the Obligation to Prosecute or Extradite (2012) and Whaling in the Antarctic (2014). We have to be prudent. The two cases are not radical change from South West Africa Case. Rather, these shall be deemed to be judged with deliberate reference to the precedents of cases on state responsibility, found out in the contentious cases and advisory opinions after South West Africa Case.

Japan-Korea Claims Agreement and the Cases on Forced Labor Issues in Korea

Hiroyuki Banzai

Jurist (30) 2019/08-


Books And Publication
















Study on the Responsibility for Internationally Wrongful Acts

Hiroyuki Banzai(Single Author)



Scholarly BookTotal Number of Pages:356ISBN:4792333342

Lecture And Oral

The Role of International Law Commission in the Process of Formation of International Customary Law

Japanese Association of International Law2006/10


Oral presentation(general)

On the Draft of Japan's Legislation of Peace and Security

Hiroyuki Banzai

(ChineseAcademy ofSocialSciences, Institute of Japanese Studies)Invitation Yes2015/08/21



Japan's Security and International Law

Hiroyuki Banzai

(Peking University)Invitation Yes2015/10/26


Outline: The theme of presentation was on legal response to changes of security environment of Japan after WWII.

Invocation of State Responsibility to Restore the Common Interests of International Community

Hiroyuki Banzai

Japanese Society of International Law2016/09/09

Japan’s Legislation for Peace and Security: From the viewpoint of international law

Hiroyuki Banzai

International Conference on Prospects for Peace and Prosperity in the New Age(Tamkang University)Invitation Yes2017/03/27


International conferenceOral presentation(invited, special)Venue:Taipei

Outline: The theme was on the significance and challenges of the Legislation for Peace and Security, especially in relation to the right to collective self-defense.

South China Sea Arbitration Award in the Development Process of the Law of the Sea: Maritime Security and Freedom of Navigation

Hiroyuki Banzai

International Seminar on Asia-Pacific Cooperative Security(International School on Disarmament and Research on Conflicts (ISODARCO))Invitation Yes2017/05/28


International conferenceOral presentation(invited, special)Venue:Taipei

Outline: South China Sea Arbitration Award was the theme of the presentation. While the Award is in the field of law of the sea, the presentation was related to those security issues which are a whole theme of this seminar.

The Role of International Law in East Asia

Hiroyuki Banzai

Jeju Forum for Peace and Prosperity(Jeju Province)Invitation Yes2017/06/01


International conferenceSymposium workshop panel(nominated)Venue:Jeju

Outline: I discussed common theme of Peace and Prosperity in East Asia from the perspective of what can be considered the most important of the various roles of international law ( sovereign equality, non-use of force and peaceful settlement of disputes) in this region today, considering the situations such as maritime conflicts in South China Sea and North Korea's nuclear and missile development efforts.

The Evolution of Rule based International System

Hiroyuki Banzai

East Asia and the Rules-Based International System: Leadership and Interests(Institute of Foreign Affairs and National Security, Wilton Park)Invitation Yes2017/11/22


International conferenceSymposium workshop panel(nominated)Venue:Seoul

Cybersecurity and International Law

Hiroyuki Banzai

New Horizons in Korean Diplomacy: Challenges, Issues, and Responses in the Era of the Fourth Industrial Revolution(Korea National Diplomatic Academy)Invitation Yes2018/12/12


International conferenceSymposium workshop panel(nominated)Venue:Seoul

The 1965 'Claims Agreement' and the Judgement of Supreme Court of Korea on Forced Labor Issues

Hiroyuki Banzai

Current issues on Japan - Korea relationship: Legal Perspective(Hiroshima City University Hiroshima Peace Institute)Invitation Yes2019/04/22


National conferenceOral presentation(invited, special)Venue:Hiroshima

Outline: In the presentation, the contents of 1965 Claims Agreement and the logic of a series of Korean courts on forced labor were dealt with from the perspective of international law.

'Due Diligence' in the Context of Cyber Security : Challenges to Traditional International Law

Hiroyuki Banzai

Jeju Forum for Peace and Prosperity 2019(Jeju Special Self-Governing Province)Invitation Yes2019/05/29


International conferenceOral presentation(invited, special)Venue:Jeju

Outline: Taking into account the difference between cyber space and allocation of territorial space of States, national security in the context of cyber were dealt with, especially for the reference to the concept of 'due diligence'.

Research Grants & Projects

Grant-in-aids for Scientific Research Adoption Situation

Research Classification:

Model of international legislation process on the system for ensuring to implement international law


Allocation Class:¥3900000

Research Classification:

International and Domestic Implementation of International legal norms establishing a common interest


Allocation Class:¥4290000

Research Classification:

International Enforcement for Domestic Implementation of International Legal Norms of Common Interests


Allocation Class:¥4290000

On-campus Research System

Special Research Project



Research Results Outline:本研究では、国際法の統合的発展の観点から問題視されてきた「国際法の分断化」について、条約制度と一般国際法制度との関係性という総論的側面と、人権・環境・本研究では、国際法の統合的発展の観点から問題視されてきた「国際法の分断化」について、条約制度と一般国際法制度との関係性という総論的側面と、人権・環境・経済・海洋という専門化が進行する個別分野の実証的研究という各論的側面を包括的に検討した。その結果、...本研究では、国際法の統合的発展の観点から問題視されてきた「国際法の分断化」について、条約制度と一般国際法制度との関係性という総論的側面と、人権・環境・経済・海洋という専門化が進行する個別分野の実証的研究という各論的側面を包括的に検討した。その結果、国際法の分断化の側面には、分野内・分野間分断化や水平的・垂直的分断化の形態が存在することがわかった。それゆえ、条約解釈による規範的統合だけでなく、運用・執行段階における実務的調整や立法段階における制度設計を含めたかたちで分断化対策としての統合論のあり方を解明することの重要性を析出した。

Foreign Researcher Acceptance Situation


Acceptance Person Affiliation Original Institution:Shanghai Academy of Social Sciences(China)


Acceptance Person Affiliation Original Institution:Western Sydney University(Australia)



Lecture Course

Course TitleSchoolYearTerm
International CooperationSchool of Law2019spring semester
International Law I ASchool of Law2019spring semester
International Law II ASchool of Law2019fall semester
Seminar (International Law) C (S)School of Law2019spring semester
Seminar (International Law) C (F)School of Law2019fall semester
Seminar (The Law of International Organization) (S)School of Law2019spring semester
Seminar (The Law of International Organization) (S)School of Law2020spring semester
Seminar (The Law of International Organization) (F)School of Law2019fall semester
Seminar (The Law of International Organization) (F)School of Law2020fall semester
Seminar ThesisSchool of Law2019fall semester
Seminar ThesisSchool of Law2019fall semester
International Law: Lecture IGraduate School of Law2019spring semester
International Law: Lecture IIGraduate School of Law2019fall semester
Special Study on International Law 2: Lecture IGraduate School of Law2019spring semester
Special Study on International Law 2: Lecture IIGraduate School of Law2019fall semester
Principles of International LawGraduate School of Law2019an intensive course(spring)
Principles of International LawGraduate School of Social Sciences2019an intensive course(spring)