For intensive research in international legal matters, consult a Law Librarian for assistance.
Just as when looking for domestic legal information, in the international area, jurisdiction is important. Entities outside of the U.S. and its states include the following, each with its own universe of information. It is also important to keep in mind that while the laws of foreign governments have the same force, within their boundaries at least, as our laws and regulations, some international organizations can make recommendations and resolutions, but often do not have any true enforcement powers.
There is one international court that bears at least some resemblance to courts we are more familiar with in a domestic setting, and that is the International Criminal Court. Their website includes a wealth of background information, including the texts of relevant treaties, and even streaming video of proceedings.
The following links might provide good starting points:
A useful reference book, in the Library on the first floor:
The Blume Library has developed some other Reserach Guides that might be helpful in researching international legal matters: