sumption may be rebutted where the substantive statute has provided guidelines for the agency to follow in exercising its enforcement powers.[1] Thus, in establishing this presumption in the APA, Congress did not set agencies free to disregard legislative direction in the statutory scheme that the agency administers. Congress may limit an agency's exercise of enforcement power if it wishes, either by setting substantive priorities, or by otherwise circumscribing an agency's power to discriminate among issues or cases it will pursue. How to determine when Congress has done so is the question left open by Overton Park.
Dunlop v. Bachowski, 421 U. S. 560 (1975), relied upon heavily by respondents and the majority in the Court of Appeals, presents an example of statutory language which supplied sufficient standards to rebut the presumption of unreviewability. Dunlop involved a suit by a union employee, under the Labor-Management Reporting and Disclosure Act, 29 U. S. C. § 481 et seq. (LMRDA), asking the Secretary of Labor to investigate and file suit to set aside a union election. Section 482 provided that, upon filing of a complaint by a union member, "[t]he Secretary shall investigate such complaint and, if he finds probable cause to believe that a violation ... has occurred ... he shall ... bring a civil action ...." After investigating the plaintiff's claims the Secretary of Labor declined to file suit, and the plaintiff sought judicial review under the APA. This Court held that
- ↑ We do not have in this case a refusal by the agency to institute proceedings based solely on the belief that it lacks jurisdiction. Nor do we have a situation where it could justifiably be found that the agency has "consciously and expressly adopted a general policy" that is so extreme as to amount to an abdication of its statutory responsibilities. See, e. g., Adam v. Richardson, 156 U. S. App. D. C. 267, 480 F. 2d 1159 (1973) (en banc). Although we express no opinion on whether such decisions would be unreviewable under § 701(a)(2), we note that in those situations the statute conferring authority on the agency might indicate that such decisions were not "committed to agency discretion."
