Here is the unpublished opinion in Chavez v. Navajo Nation Tribal Courts.

An excerpt:

The district court dismissed the case for lack of jurisdiction. The court held that Mr. Chavez’s lawsuit against the Tribal officials could not be maintained in federal court under §1983 because all of his challenges to the Tribal officials’ actions relied on Tribal law. See Burrell v. Armijo, 456 F.3d 1159, 1174 (10th Cir. 2006) (“A § 1983 action is unavailable for persons alleging deprivation of constitutional rights under color of tribal law, as opposed to state law.” (internal quotation marks omitted)); see also Polk Cnty. v. Dodson, 454 U.S. 312, 315 (1981) (observing that acting under color of state law is “a jurisdictional requisite for a § 1983 action”). Turning to the Tribe, the court held–after noting that Mr. Chavez failed to even address the Navajo Nation’s sovereignty–that Congress had not authorized suit “against tribal entities pursuant to 42 U.S.C. § 1983.” R. at 631. See Nanomantube v. Kickapoo Tribe in Kan., 631 F.3d 1150, 1152 (10th Cir. 2011) (“[A]n Indian tribe is not subject to suit in a federal or state court unless the tribe’s sovereign immunity has been either abrogated by Congress or waived by the tribe.”); E.F.W. v. St. Stephen’s Indian High Sch., 264 F.3d 1297, 1302-03 (10th Cir. 2001) (observing that tribal sovereign immunity “is a matter of subject matter jurisdiction”).
Mr. Chavez appeals.

Briefs and lower court materials are here.