Private international law is a term widely used in Europe as an alternative to conflict of laws. It is a set of rules meant to govern in legal disputes between private citizens from different countries when they interact or transact business.
Private international law is opposite to public international law which refers to the rights and interaction of countries.
Private international law is focused on the rules, called choice of law rules, used to select foreign law. Private international law is applied for example when a contract is signed in one country and is sent to another. A problem may emerge if the legislation of one country stipulates that the contract enters into force when sent and the laws of the other country provide that the contract is effective when received.
Some contemporary experts argue that the term private international law is inappropriate, as the law applied by local courts is part of national law, even if it involves also the application of international law. For that reason, a widely used term in the United States is conflict of laws.
Martin Wolff says that private international law has become national law. There is an English private international law, a German and a French private international law. These law systems differ from one another.
The choice of laws practically affects the lives of people whether it is marriage, divorce, birth and death, or commercial relationships such as competition regulation and trade.
Already in antiquity the Romans developed a system called jus gentium, or law of nations, to deal with the conflict of laws. Laws in this system applied to all foreigners and were considered as universally applicable.
The medieval jurist, Bartolus of Sassoferrato (1314–57) was the founder of the modern study of international private law.
The feudal system in medieval France resolved conflicts on the basis that the issue had a national cause of action and local law was applied, or it had a transitory locus which required the application of foreign law. The tendency of preferring local laws paved the way for a period of territorial law which replaced the universal claims of Roman law. This tendency was accompanied by the rise of national identity and sovereignty.
In the 17th century Dutch scholars Johannes Voet (1698–1704) and Ulrich Huber (1689) affirmed the primacy of territorial law over any foreign law. The conflict of laws grew after the French Revolution and the unification of Italy, above all in parts of the world under European influence. The focus shifted from territoriality to nationality. People were judged first and foremost under their national law and only rarely under the law of the country they happened to be.
As a result of this difference it is difficult to unify private international law on the basis of the agreement between countries. Partial success has been achieved at a regional level. Several European countries are harmonizing their national laws in order to have a unified treatment of some areas.
Although private international law has supranational origins, it is considered as part of national law because of the different national practices and doctrines, along with the lack of a supranational doctrine. At the same time, it is believed that a good system of private international law is the cornerstone for a stable international life.
The practical problems faced by judges in courts are no less significant. Experts of conflict of laws have to choose the legal system that will lead to the most just ruling and have to be able to explain the reason for choosing such a solution.
Legal experts throughout the centuries have been trying, but have failed to find a universal solution for fair choice-of-law rules all over the world. One of the reasons is that some legal systems are based on nationality as a major criterion and other systems are based on territoriality. In addition, judges are not willing to follow theoretical solutions offered by scholars. They will rather make a ruling on the basis of their view of what justice requires.
However, scholars continue efforts to achieve uniformity and equality in private international law.
One of the efforts to build a bridge between different legal systems is the Hague Conference on Private International Law (or HCCH). Founded in 1893 with the mission to "work for the progressive unification of the rules of private international law," the organization has 72 members from all continents.
Between 1951 and 2008, the Conference adopted 38 international conventions, most of them in the field of abolition of legislation, international child abduction, intercountry adoption, divorces and access to justice.