And the extent of the burden that will be tolerated will of course depend on the nature of the local interest involved, and on whether it could be promoted as well with a lesser impact on interstate activities.Pike v. Bruce Church, Inc., 397 U.S. 137, 142, 90 S.Ct. 844, 847, 25 L.Ed.2d 174 (1970); see also Washington State Building and Construction Trades Council v. Spellman, 684 F.2d 627, 630-31 (9th Cir. 1982), cert. denied, 461 U.S. 913, 103 S.Ct. 1891, 77 L.Ed.2d 282 (1983). The ordinance does not regulate evenhandedly, Evergreen argues, since waste from outside the district is not treated the same as waste from within the district.

Our colleagues contend that our application of Rule 24(a)(2) is inconsistent with our precedent. They rely on a line of cases in which we have held that an intervenor had a significant protectable interest under Rule 24(a)(2) deriving neither from an express statutory interest nor from a real property right. Judge Bumatay Dissent at 1111-13 (citing Idaho v. Freeman , 625 F.2d 886, 887 (9th Cir. 1980) ; Washington State Bldg. & Constr. Trades Council, AFL-CIO v. Spellman , 684 F.2d 627, 629–30 (9th Cir. 1982) ; Sagebrush Rebellion, Inc. v. Watt , 713 F.2d 525, 526–28 (9th Cir. 1983) ; Idaho Farm Bureau Fed'n v. Babbitt , 58 F.3d 1392 (9th Cir. 1995) ). In Idaho v. Freeman , we held that the National Organization for Women, a leading national advocate of the Equal Rights Amendment to the U.S. Constitution, had a right to intervene in a suit challenging procedures for the ratification of the proposed Amendment.

Id.; United States ex rel. McGough v. Covington Technologies Co., 967 F.2d 1391, 1394 (9th Cir. 1992); Washington State Bldg. Constr. Trades Council v. Spellman, 684 F.2d 627, 630 (9th Cir.), cert. denied, 461 U.S. 913, 103 S.Ct. 1891, 77 L.Ed.2d 282 (1982). A.

Although this court has never articulated a standard for review of orders denying intervention of right, it has in practice reviewed such orders de novo. See Sagebrush Rebellion, Inc. v. Watt, 713 F.2d 525, 527-29 (9th Cir. 1983) (conducting de novo review of denial of intervention); Washington State Building and Construction Trades Council v. Spellman, 684 F.2d 627, 629-30 (9th Cir. 1982) (same) cert. denied, 461 U.S. 913, 103 S.Ct. 1891, 77 L.Ed.2d 282 (1983); Idaho v. Freeman, 625 F.2d 886, 887 (9th Cir. 1980) (same). We follow that practice here.

More recently we have had occasions to apply this test in contexts which closely parallel this one. In Washington State Building Construction Trades v. Spellman, 684 F.2d 627 (9th Cir. 1982), cert. denied, ___ U.S. ___, 103 S.Ct. 1891, 77 L.Ed.2d 282 (1983), we held that a public interest group was entitled as a matter of right to intervene in an action challenging the legality of a measure which it had supported. This court stated that "Rule 24 traditionally has received a liberal construction in favor of applications for intervention."

See 7C C. Wright, A. Miller, M. Kane, Federal Practice and Procedure Section(s) 1908 at 263 (2d ed. 1986 Supp. 1996). Dr. Silver cites Idaho Farm Bureau Fed'n v. Babbitt, 58 F.3d 1392 (9th Cir. 1995), for the proposition that he "is entitled as a matter of right to intervene in an action challenging the legality of a measure [he] has supported." Id. at 1397; see also Yniguez v. Arizona, 939 F.2d 727 (9th Cir. 1991); Sagebrush Rebellion, Inc. v. Watt, 713 F.2d 525, 527-28 (9th Cir. 1983); Washington State Bldg. Constr. Trades Council v. Spellman, 684 F.2d 627, 630 (9th Cir. 1982), cert. denied, 461 U.S. 913 (1983). Our circuit and the Fifth Circuit require that "[the] interest in the proceedings be `direct, substantial, and legally protectable.'"

Although the waste-generators contend that the district court's denial of appellant's motion to intervene as of right should be reviewed for an abuse of discretion, we traditionally conduct a de novo review of such orders. See, e.g., Sagebrush Rebellion, Inc. v. Watt, 713 F.2d 525, 527 (9th Cir. 1983); Washington State Building Construction Trades Council v. Speliman, 684 F.2d 627, 629-30 (9th Cir. 1982), cert. denied, 461 U.S. 913, 103 S.Ct. 1891, 77 L.Ed.2d 282 (1983); Smith v. Pangilinan, 651 F.2d 1320 (9th Cir. 1981); Idaho v. Freeman, 625 F.2d 886, 887 (9th Cir. 1980); County of Fresno v. Andrus, 622 F.2d 436, 438 (9th Cir. 1980); Legal Aid Society v. Dunlop, 618 F.2d 48, 49-50 (9th Cir. 1980); Johnson v. San Francisco Unified School District, 500 F.2d 349, 352-54 (9th Cir. 1974). We do so because our review of the district court's decision involves application of a rule of law to the established facts, and because the issue primarily involves consideration of legal concepts in the mix of fact and law.

. . . [and] preempts any state attempt to regulate materials covered by the Act for safety purposes"); Jersey Cent. Power Light Co. v. Lacey Tp., 772 F.2d 1103, 1110-12 (3d Cir. 1985) (holding township ordinance prohibiting importation of spent nuclear fuel or other radioactive waste for the purpose of storage was preempted by AEA); People of Ill. v. Gen. Elec. Co., 683 F.2d 206, 208, 215 (7th Cir. 1982) (holding that AEA preempts state statute prohibiting "transport into State for disposal or storage of any spent nuclear fuel which was used in any power generating facility located outside State"); Wash. State Building Const. Trades Council v. Spellman, 684 F.2d 627, 630 (9th Cir. 1982); Long Island Lighting Co. v. County of Suffolk, 628 F. Supp. 654, 662-66 (E.D.N.Y. 1986) (holding preempted by AEA municipal ordinance that prohibited certain aspects of an emergency-response test required before the Nuclear Regulatory Agency would license nuclear power plant). The Court in Pacific Gas went on to hold that the state statute at issue there was aimed, not at "radiation hazards," but at "economic problems."

Without elaborating on the definition of a " significantly protectable" interest, CCAC maintained that Courts of Appeals had routinely found sufficient interests to permit intervention by citizens' groups like CCAC in cases in which the validity of statutes and regulations supported by those groups was being challenged. Id. (citing three Ninth Circuit cases, United States v. Stringfellow, 783 F.2d 821 (9th Cir.1986), vacated on other grounds, 480 U.S. 370, 107 S.Ct. 1177, 94 L.Ed.2d 389 (1987); Sagebrush Rebellion, Inc. v. Watt, 713 F.2d 525 (9th Cir.1983); and Washington State Building and Construction Trades Council, AFL-CIO v. Spellman, 684 F.2d 627 (9th Cir.1982), cert. denied sub nom.Don't Waste Washington Legal Defense Foundation v. Washington, 461 U.S. 913, 103 S.Ct. 1891, 77 L.Ed.2d 282 (1983)).           In its brief in opposition, Hyland argues that the interest asserted by a prospective intervenor must be " direct, as opposed to remote or contingent."

Id. The Evergreen court found that the ordinance regulated evenhandedly because "evenhandedness requires simply that most out-of-state waste be treated no differently than in-state waste." Id. at 1484, citing Washington State Trades Council v. Spellman, 684 F.2d 627, 631 (9th Cir. 1982), cert. denied, 461 U.S. 913, 103 S.Ct. 1891, 77 L.Ed.2d 282 (1983). Because the ordinance regulated waste disposal evenhandedly, the Evergreen court applied the Pike balancing test, noted supra, which provides that where a State acts evenhandedly to promote a legitimate local concern, and the effect on interstate commerce is merely incidental, the state regulation will be upheld unless the burden on such commerce is clearly excessive in relation to the putative local benefits.