Here is the unpublished memorandum. An excerpt:
Appellants conceded at oral argument that the Navajo Nation has not retained the right to exclude nonmembers on U.S. Highway 160. Consequently, the highway is the equivalent of non-Indian fee land for jurisdictional purposes, and this case is governed by Strate v. A-1 Contractors, 520 U.S. 438 (1997). See Strate, 520 U.S. at 455-56.
Briefs and oral argument materials here.
Federal district court materials here.
Tribal court materials here.