American Indian or Native American law comprises Federal, State and Tribal Law.
There are over 550 tribes in the USA, each with its own laws and justice systems. Tribal laws are internal or 'domestic' laws which apply only to the members of a tribe. 'Tribal law' refers generically to the laws of various tribes. Before the arrival of European nations and the formation of the United States, the laws of Indian tribes (or 'nations') usually took the form of informal, common-law rules. Today, tribal law generally includes the authority to decide tribal membership, enforce criminal laws against members of the tribe, enact domestic laws, and regulate the activities of the people residing within tribal territories. Native Americans are also subject to US laws. Apart from laws that affect all Americans, Federal Indian law is the law that describes and controls the relationships between American Indian tribes, the United States, and the states. Federal Indian law consists mostly of federal common law that derives from the thousands of cases interpreting Indian treaties, Federal Indian-affairs legislation, and the one US Constitutional provision that deals with Indian affairs (the Indian commerce clause). In addition, treaties entered into in the late 1800s create the framework for government-tribal relations for particular tribes.
Most government law relating to Native Americans and tribal activities is Federal rather than State. This Research Guide focuses on tribal law and Federal laws affecting Native Americans.
We recommend starting your research with secondary sources such as commentary, books and journal articles.
An excellent and clear introduction to Native American Law and researching it is Kelly Kunsch, 'A legal practitioner's guide to Indian and tribal law research' (2016) 5 American Indian Law Journal 102-138 (open access).
See also the National Indian Law Library (NILL) (open access) which includes useful research guides and other resources. It's Tribal Law Gateway lists hundreds of tribes. Each tribal page links to available online versions of tribal constitutions and codes, case law, treaties and other sources of Indian and tribal law.
For useful and succinct introductions to Native American legal history, customary law, and the current position of tribal law and Native Americans within the US legal system, see the following books and chapters: