25 CFR § 900.4 - Effect on existing tribal rights.
Nothing in these regulations shall be construed as:
(a) Affecting, modifying, diminishing, or otherwise impairing the sovereign immunity from suit enjoyed by Indian tribes;
(b) Terminating, waiving, modifying, or reducing the trust responsibility of the United States to the Indian tribe(s) or individual Indians. The Secretary shall act in good faith in upholding this trust responsibility;