Definition of International and Private International Law

international law (1786) The legal system governing the relationships between countries; more modernly, the law of international relations, embracing not only countries but also such participants as international organizations and individuals (such as those who invoke their human rights or commit war crimes). — Also termed public international law; law of nations; law of nature and nations; jus gentium; jus gentium publicum; jus inter gentes; foreign-relations law; interstate law; law between states (the word state, in the latter two phrases, being equivalent to nation or country). Cf. transnational law.

“[I]nternational law or the law of nations must be defined as law applicable to states in their mutual relations and to individuals in their relations with states. International law may also, under this hypothesis, be applicable to certain interrelationships of individuals themselves, where such interrelationships involve matters of international concern.” Philip C. Jessup, A Modern Law of Nations 17 (1948).

“International law is the legal order which is meant to structure the interaction between entities participating in and shaping international relations. This rather wide definition deliberately avoids a reference to States. Although States play a significant role in today's international relations, they are not the only actors. International organizations and other international law subjects, as well as groups of individuals, non-governmental organizations, and even individuals, contribute to the development of international relations. The development that groups of individuals and individuals participate in international relations acting on their own and not on behalf of States is a recent one.” Rüdiger Wolfrum, “International Law,” in 5 The Max Planck Encyclopedia of Public International Law 820, 821 (Rüdiger Wolfrum ed., 2012) (citations omitted).

- customary international law (1905) International law that derives from the practice of states and is accepted by them as legally binding. • This is one of the principal sources or building blocks of the international legal system.

- private international law (1834) International conflict of laws. • Legal scholars frequently lament the name “private international law” because it misleadingly suggests a body of law somehow parallel to public international law, when in fact it is merely a part of each legal system's private law. — Also termed international private law; jus gentium privatum; intermunicipal law; comity; extraterritorial recognition of rights. See conflict of laws (2).

“The expression ‘international private law’ is no doubt a slight improvement on ‘private international law,’ as it points out that the rules which the name denotes belong to the domain of private law. But the name, improve it as you will, has the insuperable fault of giving to the adjective ‘international’ a meaning different from the sense in which it is generally and correctly employed.” A.V. Dicey & A. Berriedale Keith, A Digest of the Law of England with Reference to the Conflict of Laws 14 (3d ed. 1922).

“[A] word must be said about the name or title of the subject. No name commands universal approval. The expression ‘Private International Law,’ coined by Story in 1834 [Joseph Story, Commentaries on the Conflict of Laws § 9 (1834)], and used on the Continent by [Jean Jacques Gaspard] Foelix in 1838, has been adopted by Westlake and Foote and most French authors. The chief criticism directed against its use is its tendency to confuse private international law with the law of nations or public international law, as it is usually called. There are obvious differences between the two. The latter primarily governs the relations between sovereign states and it may perhaps be regarded as the common law of mankind in an early state of development; the former is designed to regulate disputes of a private nature, notwithstanding that one of the parties may be a private state. There is, at any rate in theory, one common system of public international law …; but … there are as many systems of private international law as there are systems of municipal law.” G.C. Cheshire, Private International Law 15 (6th ed. 1961).

International Law, Black’s Law Dictionary, (12th ed. 2024). 

conflict of laws (1827)

1. 1. A difference between the laws of different states or countries in a case in which a transaction or occurrence central to the case has a connection to two or more jurisdictions. — Often shortened to conflicts. Cf. choice of law.

   “When a court is called upon to decide an ordinary case or controversy, the operative facts upon which judgment is based have, or are assumed to have, occurred within the territorial limits of the state or country where the court sits. Very often, however, the operative facts, or a part of them, have a connection with some other jurisdiction. Thus, a court may have to determine the validity or legal effect of an agreement as a contract in a case where the agreement was reached in another state or country, or the offer was accepted there. Again, a tort claim may be predicated upon injury which has been incurred outside the territorial limits of the state where the court sits. Or, the validity of a marriage celebrated abroad or that of a foreign divorce may be the factor upon which the conflicting claims of the parties depend. In the field of property the issue may turn upon the legal effect of an attempted transfer in one jurisdiction of property, real or personal, located in another or upon that of a foreign will. In cases such as these, which are illustrative only and not exhaustive, the foreign fact element raises questions of the effect to be given at the forum to foreign law. That branch of the law which deals with questions of the operative effect at the forum of foreign law because of a foreign fact element in the case is sometimes called Private International Law but in this country more usually Conflict of Laws.” George Wilfred Stumberg, Principles of Conflict of Laws 1 (2d ed. 1951).

   • - conflict of personal laws (1905)

     1. 1. A difference of laws between a jurisdiction's general laws and the laws of a racial or religious group, such as a conflict between federal law and American Indian tribal law.

     2. 2. A difference between personal laws. See personal law.

   • - false conflict of laws (1966)

     1. 1. A situation resembling but not embodying an actual conflict because the potentially applicable laws do not differ, because the laws' underlying policies have the same objective, or because one of the laws is not meant to apply to the case before the court.

     2. 2. The situation in which, although a case has a territorial connection to two or more states whose laws conflict with one another, there is no real conflict because one state has a dominant interest in having its law chosen to govern the case — hence there is no real conflict.

     3. 3. The situation in which the laws of all states that are relevant to the facts in dispute either are the same or would produce the same decision in the case. — Often shortened to false conflict.

2. 2. The body of jurisprudence that undertakes to reconcile such differences or to decide what law is to govern in these situations; the principles of choice of law. — Often shortened (in sense 2) to conflicts. — Also termed (in international contexts) private international law; international private law. See private international law under international law.

   “The phrase [conflict of laws], although inadequate, because it does not cover questions as to jurisdiction, or as to the execution of foreign judgments, is better than any other.” Thomas E. Holland, The Elements of Jurisprudence 421 (13th ed. 1924).

   Conflict of Laws, Black’s Law Dictionary, (12th ed. 2024).