An important first step for beginning research in foreign law is understanding the country's legal system. A country's legal system affects the authoritative value of legal materials and can provide insight into the types of documents you can expect to find (or not). The majority of countries have civil law or common law legal systems.
Common Law: In a common law legal system, judicial decisions establish legal precedents. Sources of law in common law countries include judicial opinions along with scattered statutes. Examples of common law countries include the United States, Australia, and the United Kingdom (except for Scotland, Guernsey, and Jersey).
Civil Law: In a civil law system, codified statutes are the most important source of law. These written codes are comprehensive, covering nearly every area of law, and frequently updated. Judicial decisions do not have precedential value. Examples of civil law countries include France, Germany, and Brazil.
Religious Law: Religious law systems are based on Islam or Judaic law. Typically, religious law applies only to specific issues such as marriage. Countries with religious legal systems usually also have a civil or common law system.
Customary Law: Customary law is typically unwritten (e.g., elders oversee customary laws in a small community) and comes into play with specific issues like inheritance and marriage. Generally, a country that follows customary laws also has another type of legal system, such as a civil or common law system.
Mixed System: Countries with mixed legal systems incorporate elements from more than one legal tradition.
A quick, easy way to identify a country's legal system is to use JuriGlobe World Legal Systems. On this free website, you can pull up an alphabetical list of countries around the world and their corresponding legal systems or pull up lists of the various legal systems and all of those countries that have that system.
Another source to learn about countries around the world and to identify their legal systems is the CIA World Factbook. Additionally, country-specific legal research guides will discuss that country's legal system and the sources of law for that country.