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For many years, Public and Private International Law were regarded as totally unrelated; each having a distinct subject covered by its scope. Public International law governs the relations between States and also between States and other international entities. On the other hand, Private International Law deals with relations of private actors (individuals) engaged in cross-border transactions. It is also known as “conflict of laws” because its main role is to find the substantive applicable law to govern the relationship between the parties.[1] However, such a distinction is no longer valid to solve international problems nowadays. Both dimensions of international law interact in many ways and share common principles.

Therefore, in what ways does the overlap of Public and Private International Law manifests itself?

  • Public International Law Principles applied in Conflict of Law Cases

Certain Public International Law concepts were recognized and accepted as rules of Conflict of Laws such as[2]:

  • The immunities of sovereigns and States:

The Public International Law principle of sovereign immunity was used in English Common Law courts in the famous case of Duke of Drunswick v. King of Hanover[3]. The court considered that the sovereign prince is exempt from the jurisdiction of courts where he resides. Similarly, this principle was used in the Sayce v. Ameer Ruler Sadiq Muhammad[4].

  • The immunities of diplomatic agents and related matters:

Another well-known principle of Public International Law influencing most national diplomatic laws is the immunity of diplomatic agents and was clearly applied in the English case of Magdalene Steam Navigation Co. v. Martin[5].

  • The recognition of new States, of new governments and of state jurisdictions:

The issue of legal system recognition in Private International Law is similar to Public International Law rules of State recognition.


  • Today’s international problems have the public and private aspects

Some pressing international problems cannot be solved from solely the Public or Private International Law perspective such as[6]:

  1. International Human Rights: Human rights treaties impose obligations on States to ensure these rights. Such treaties are grounded in Public International Law. But what if human rights violations were committed by non-State actors? Corporations for example can violate human rights. The UN Human Rights Council issuing the UN Guiding Principles on Business and Human Rights proves that the interaction between Public and Private International Law is essential to establish and define corporate duty to respect human rights.[7]
  2. Corruption: It is no longer regarded as a national problem but rather as an international one. To fight corruption on the international level States must commit to enact such laws. For this purpose many treaties were established such as: Convention on Combating Bribery of Foreign Public Officials in International Business Transactions (OECD Convention)[8] and the UN Convention against Corruption[9]. This means that tackling anti-corruption internationally requires both a Public International Law approach and that of national laws.[10]
  3. Cases before the International Court of Justice (ICJ): The ICJ is the main judicial organ of the United Nations. It addresses boundary or treaty disputes between States; that is, Public International Law matters.[11] However, the following list of cases are examples of how the ICJ applies both Public and Private International Law while resolving some disputes[12]:
  • Payment of Various Serbian Loans Issued in France Case[13]: The Court adopted Private International Law rules to resolve the dispute and considered that such rules can govern relations between States.
  • Boll case also known as Guardianship of an Infant Case[14]: The Court interpreted a Private International Law treaty to resolve the dispute.
  • Nottebohm Case[15], Barcelona Traction Case[16], Diallo Case[17]: The Court used in all these cases the domestic law of States as relevant facts to resolve the disputes.
  • Public International Law Treaties regulating Private Relations

Some multilateral treaties are signed and ratified by States to govern activities carried out by private actors such as[18]:

  1. New York Convention on the Recognition and Enforcement of Foreign Arbitral Awards: guides States’ courts on when to give effect to an agreement to arbitrate and when to recognize and enforce foreign arbitral awards.[19]
  2. UN Convention on Contracts for the International Sale of Goods (CISG): establishes rules concerning international contractual obligations.[20]
  3. Convention on the Law Applicable to Contractual Obligations (Rome Convention): establishes a common choice of law rules for contracts within the European Union.[21]

Public and Private International Law interact in many ways especially when resolving international disputes. It is about time to unify all those principles under one international law in an attempt to establish a legal framework regulating the activities of both public and private actors. International relations nowadays prove that there is a large interaction between all its actors. Such an interaction calls for action: the first step must be at Law Schools. Legal practitioners will not be able to properly understand the overlapping of Public and Private Law practically before international courts, if they do not recognize such an interaction theoretically. So how will the shift from division to unification look like in the future?     

[1] S. Karamanian, “Public International Law Versus Private International Law: Reconsidering The Distinction”, George Washington University Law School, p. 33.

[2] G. Narasimhan and W. John, “The Interaction Between Public and Private International Law- Some New Trends”, National Law School of India University, Bangalore, p. 99.

[3] Duke of Drunswick v. King of Hanover (1848).

[4] Sayce v. Ameer Ruler Sadiq Muhammad (1952).

[5] Magdalene Steam Navigation Co. v. Martin (1859).

[6] S. Karamanian, supra note 1.

[7] Id.

[8] Convention on Combating Bribery of Foreign Public Officials in International Business Transactions, opened for signature December  17, 1997.

[9] U.N Convention against Corruption, opened for signature December 9, 2003.

[10] S. Karamanian, supra note 1.

[11] Article 34 of the ICJ Statute.

[12] D. Arroyo and M. Mbengue, “Public and Private International Law in International Courts and Tribunals: Evidence of an Inescapable Interaction”, Columbia Journal of Transnational Law, 2018, p.10.

[13] Payment of Various Serbian Loans Issued in France (Fr. v. Yugo.), Judgment, 1929 P.C.I.J No. 20 (July 12).

[14] Guardianship of an Infant (Neth. v. Swed.), Judgment, 1958 I.C.J (Nov. 28). 

[15] Nottebohm (Liech. v. Guat.), Second Phase, 1955 I.C.J. (Apr. 6). 

[16] Barcelona Traction, Light and Power Co. (Belg. v. Spain), Second Phase, 1970 I.C.J. (Feb. 5).

[17] Ahmadou Sadio Diallo (Guinea v Dem. Rep. Congo), Preliminary Objections, 2007 ICJ. No. 924, (May 24). 

[18] S. Karamanian, supra note 1.

[19] U.N. Convention on the Recognition and Enforcement of Foreign Arbitral Awards, opened for signature on June 10, 1958.

[20]U.N. Convention on Contracts for the International Sale of Goods, opened for signature on April 11, 1980.

[21] Rome Convention on the Law Applicable to Contractual Obligations, signed on June 19, 1980.

Rosabelle Saba
Notice: This article is protected under Lebanese Copyrights Law. No one shall copy more than 25% of this article without referring to its main source.


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