List of national legal systems
Common law is currently in practice in Ireland, most of the United Kingdom (England and Wales and Northern Ireland), Australia, New Zealand, Bangladesh, India (excluding Goa), Pakistan, South Africa, Canada (excluding Quebec), Hong Kong, the United States (on a state level excluding Louisiana), and many other places. In addition to these countries, several others have adapted the common law system into a mixed system. For example, Nigeria operates largely on a common law system, but incorporates religious law.
Sources of international law
Some treaties are the result of codifying existing customary law, such as laws governing the global commons, and "jus ad bellum". While the purpose is to establish a code of general application, its effectiveness depends upon the number of states that ratify or accede to the particular convention. Relatively few such instruments have a sufficient number of parties to be regarded as international law in their own right. The most obvious example is the 1949 Geneva Conventions for the Protection of War Victims.