Deference to Agency Interpretation

1.There is sufficient ambiguity in the statute and the regulations that we might defer to the Service's interpretation anyway. See, e.g., First National Bank v. Comptroller of Currency, [1992] USCA7 129; 956 F.2d 1360, 1365 (7th Cir.1992). 

2.But such deference applies only to "reasoned and consistent" agency positions; it does not apply to "agency litigating positions that are wholly unsupported by regulations, rulings, or administrative practice." Bowen v. Georgetown University Hospital, [1988] USSC 187; 488 U.S. 204, 212[1988] USSC 187; , 109 S.Ct. 468, 473[1988] USSC 187; , 102 L.Ed.2d 493 (1988).

Harco Holdings Incorporated v United States [1992] USCA7 1187; 977 F.2d 1027 (9 November 1992)

And, as the Supreme Court has noted repeatedly, "In order for an agency interpretation to be granted deference, it must be consistent with the congressional purpose. Espinoza v. Farah Mfg. Co., [1973] USSC 232; 414 U.S. 86 (94 S.Ct. 334[1973] USSC 232; , 38 L.Ed.2d 287) (1973); Red Lion Broadcasting Co. v. FCC, 395 U.S. 367, 381, (89 S.Ct. 1794, 23 L.Ed.2d 371) (1969)." Morton v. Ruiz, 415 U.S. 199, 237, 94 S.Ct. 1055, 1075[1974] USSC 29; , 39 L.Ed.2d 270 (1974)Citizens for Better Environment v Environmental Protection Agency [1979] USCA7 308; 596 F.2d 720; 12 ERC 1657, 13 ERC 1094, 9 Envtl. L.; Rep. 20,092 (16 May 1979)
Further Judicial deference to agency interpretations is normally justified by the agency's expertise in the regulated subject matter. See Pension Benefit Guar. Corp. v. LTV Corp., [1990] USSC 108; 496 U.S. 633, 651-52 (1990) ("[A]gency expertise is one of the principal justifications behind Chevron deference."). The agency possesses no expertise, however, that qualifies it to determine whether the rural subsistence priority applies to navigable waters. The issue "is a pure question of statutory construction for the courts to decide." INS v. Cardoza-Fonseca, [1987] USSC 32; 480 U.S. 421, 446 (1987); Chevron, U.S.A., Inc. v. Natural Res. Def. Council, Inc., 467 U.S. 837, 843 n.9 (1984) "The judiciary is the final authority on issues of statutory construction.".and that  the issue presented is a question of pure law and does not implicate agency expertise in any meaningful way, we need  not defer under Chevron . . . ." Magana-Pizano v. INS, [1999] USCA9 704; 200 F.3d 603, 611 n.11 (9th Cir. 1999)