Foreign law is the law of a non-U.S. jurisdiction as it is applied in that jurisdiction, and in other jurisdictions (including in U.S. and international courts) under choice of law rules. Comparative law is not a separate body of rules and principles, but is a method of the comparative study of two or more different legal systems. Some sources also refer to the law of other countries as international law, global law, or world law.
Foreign law is separate from international law, the rules and principles dealing with the conduct of states and of international organizations as well as with some of their relations with persons (as defined by the Restatement 3d of Foreign Relations). Some sources refer to transnational law, relations which don’t fit neatly in public and private international law. This can include national court rulings on international issues (banking, commercial law), areas of law that cross national boundaries (such as trade law), and treaties governing transactions. Transnational law overlaps with and can be found in sources for either international or foreign law.
Research in foreign law usually involves searching for the primary materials of other countries: constitutions, statutes, codes, regulations, and court judgments or opinions. Research can also involve searching for translations of primary materials, and use of secondary sources, either legal publications of other countries, or U.S. publications on the law of other countries.
Foreign law jurisdictions may be either civil law or common law jurisdictions, or sometimes use customary or religious law or a mix of those with civil or common law. In civil law jurisdictions, stare decisis may not apply, so court decisions may include few citations and little background on the facts of the case. Full-text opinions may not be published. Codes are usually well-organized and each article may provide a complete picture of that area of the law. The official legal publication for statutes and sometimes regulations or case law is an official gazette or official journal. For more explanation of civil law systems, see the Federal Judicial Center’s A Primer on the Civil-Law System.
In common law jurisdictions, stare decisis applies: case law serves as precedent for later decisions and decisions of lower courts. There are sources like Shepards and Keycite for verifying the status of case law precedents. Codes and statutes also serve as legal authority.
In practice, foreign law may be used to advise U.S. clients abroad or doing business abroad, and to advise foreign clients in the United States. Choice of law provisions or conflict of law rules may direct the practitioner and courts to the internal law of other countries. The study of comparative law may have the researcher study the other law of other countries to compare with that of the United States or other jurisdictions in subjects like human rights.
The researcher in foreign law should proceed with caution and will encounter difficulties in research. Official sources of other countries are published in their official languages. English-language translations may not be current, accurate, or even available. There may be limited published sources of law for other countries, especially for case law of civil law countries. Few libraries have large foreign law collections in print form. And because legal systems and publications vary from those of the United States, the researcher should start by finding information to understand the country’s legal system.