with whom WALD, Circuit Judge, joins, concurring:
I join the court’s holding that the Tribes have failed to identify a specific legal obligation constraining the Attorney General’s discretion to choose which water rights claims to file in the Idaho State proceeding. I write separately to emphasize two points that are implicit in the court’s opinion.
First, as the federal government’s trust responsibility toward a particular tribal resource increases in scope, the Attorney General’s prosecutorial discretion contracts. Thus, a conclusion that the Attorney General’s discretion is unreviewable under Heckler v. Chaney, 470 U.S. 821, 105 S.Ct. 1649, 84 L.Ed.2d 714 (1985), is tantamount in the instant case to a decision that the government’s trust obligation lacks the specificity required after United States v. Mitchell, 463 U.S. 206, 224-25, 103 S.Ct. 2961, 2971-72, 77 L.Ed.2d 580 (1983) (Mitchell II), and United States v. Mitchell, 445 U.S. 535, 542, 100 S.Ct. 1349, 1353, 63 L.Ed.2d 607 (1980) (Mitchell I), to impose an affirmative and enforceable duty. Because any fiduciary relationship established by the off-reservation hunting right in the Fort Bridger Treaty does not provide the requisite specificity, the court has no occasion to decide what the scope of the government’s duties might be in a more compelling circumstance. See, e.g., Joint Tribal Council of the Passamaquoddy Tribe v. Morton, 528 F.2d 370, 379 (1st Cir.1975); Fort Mojave Indian Tribe v. United States, 23 Cl.Ct. 417, 425-26 (1991).
Furthermore, to decide the instant case the court need not appraise the merits of the Tribes’ off-reservation water rights claims. Instead, the court has only to evaluate the nature of the government’s duty as expressed in the underlying substantive law— namely, the Fort Bridger Treaty. As the court’s opinion indicates, the Tribes’ contingent hunting right is insufficient to impose a protective trust obligation on the federal government. Opinion at 1482-1483. Having identified no other viable source of the government’s duty, the Tribes therefore have no claim to the Attorney General’s assistance in filing their claims.