Any Indian tribe shall have the right to organize for its common welfare, and may adopt an appropriate constitution and bylaws, and any amendments thereto, which shall become effective when—
(1) ratified by a majority vote of the adult members of the tribe or tribes at a special election authorized and called by the Sec - retary under such rules and regulations as the Secretary may prescribe; and
(2) approved by the Secretary pursuant to subsection (d) of this section.
25 U.S.C. § 5123.
Many constitutions date from the 1930s and 1940s. For a comment about these constitutions, see Matthew Fletcher, The Myth of the Model IRA Constitution?, Turtle Talk (Nov. 21, 2007).
Many tribal constiitutions are published with Tribal Codes.
For a list of constitutions and codes of Washington tribes, see this page.
HeinOnline's Indigenous Peoples of the Americas: History, Culture & Law (formerly American Indian Law Collection includes many constitutions and by-laws separately published by the Office of Indian Affairs. Materials from tribes in Washington State are listed with tribal codes, above.
HeinOnline and the Library of Congress offer many of the same documents, so why list both sets here? HeinOnline has better searching options, but it is a licensed database and is only available to subscribers (including the UW). Access to the Library of Congress digital collection is free.