volved in the proper ordering of its priorities. Similar concerns animate the principles of administrative law that courts generally will defer to an agency's construction of the statute it is charged with implementing, and to the procedures it adopts for implementing that statute. See Vermont Yankee Nuclear Power Corp. v. Natural Resources Defense Council, Inc., 435 U. S. 519, 543 (1978); Train v. Natural Resources Defense Council, Inc., 421 U. S. 60, 87 (1975).
In addition to these administrative concerns, we note that when an agency refuses to act it generally does not exercise its coercive power over an individual's liberty or property rights, and thus does not infringe upon areas that courts often are called upon to protect. Similarly, when an agency does act to enforce, that action itself provides a focus for judicial review, inasmuch as the agency must have exercised its power in some manner. The action at least can be reviewed to determine whether the agency exceeded its statutory powers. See, e. g., FTC v. Klesner, 280 U. S. 19 (1929). Finally, we recognize that an agency's refusal to institute proceedings shares to some extent the characteristics of the decision of a prosecutor in the Executive Branch not to indict—a decision which has long been regarded as the special province of the Executive Branch, inasmuch as it is the Executive who is charged by the Constitution to "take Care that the Laws be faithfully executed." U. S. Const., Art. II, § 3.
We of course only list the above concerns to facilitate understanding of our conclusion that an agency's decision not to take enforcement action should be presumed immune from judicial review under § 701(a)(2). For good reasons, such a decision has traditionally been "committed to agency discretion," and we believe that the Congress enacting the APA did not intend to alter that tradition. Cf. 5 Davis § 28:5 (APA did not significantly alter the "common law" of judicial review of agency action). In so stating, we emphasize that the decision is only presumptively unreviewable; the pre-
