In the years since Justice Jackson's observation, the federal courts have continued to apply the intelligible-principle doctrine, which allows a great deal of legislative power to be delegated to administrative agencies without interference from the courts. The seminal case, Chevron, which established the deferential review standard, was decided in 1984. But the courts still are examining foundational questions about agency power, and the academic articles examining agency power and the implications of Chevron are plentiful.
At the federal level, there are two main types of deference for agency actions: "Chevron deference," named for the standard developed in that case, and "Skidmore deference," named for the concept developed in Skidmore v Swift & Co, 323 US 134 (1944). The deference accorded to an agency depends on the kind of action involved. In practice, federal courts have struggled to categorize administrative actions and determine whether Chevron or Skidmore should apply.
In Chevron, the Supreme Court stated the following rule for reviewing agency action:
When a court reviews an agency's construction of the statute which it administers, it is confronted with two questions. First, always, is the question whether Congress has directly spoken to the precise question at issue. If the intent of Congress is clear, that is the end of the matter; for the court, as well as the agency, must give effect to the unambiguously expressed intent of Congress. If, however, the court determines Congress has not directly addressed the precise question at issue, the court does not simply impose its own construction on the statute, as would be necessary in the absence of an administrative interpretation. Rather, if the statute is silent or ambiguous with respect to the specific issue, the question for the court is whether the agency's answer is based on a permissible construction of the statute.
Chevron USA, Inc, 467 US at 842-43 (1984).
The federal courts accept vast delegations of power to administrative agencies under the intelligible-principle doctrine. See generally, Whitman v American Trucking Ass'n, 531 US 457, 474-75 (2001). This often permits vast "gaps" in the statutory langauge. The federal courts accept the premise that administrative agencies can fill these gaps. Chevron, 467 US at 843. Where Congress has explicitly allowed an agency to fill a gap, a regulation doing so is valid unless it is "arbitrary, capricious, or manifestly contrary to the statute." Id. at 844. The United States Supreme Court indicated that where Congress has only implicitly delegated a particular question to an agency, "a court may not substitute its own construction of a statutory provision for a reasonable interpretation made by the administrator of an agency" - a somewhat lower level of deference. Id.
The case for deference to an agency is strong when a statute "involves conflicting policies" and where "more than ordinary knowledge respecting the matters subjected to agency regulation" is necessary to administer the statutory scheme. Id. at 845.
The Supreme Court justified its deference to agencies by noting that as between the courts and the executive branch, the executive is more responsive to the people:
Judges are not experts in the field, and are not part of either political branch of the Government. Courts must, in some cases, reconcile competing political interests, but not on the basis of the judges' personal policy preferences. In contrast, an agency to which Congress has delegated policy-making responsibilities may, within the limits of that delegation, properly rely upon the incumbent administration's views of wise policy to inform its judgments. While agencies are not directly accountable to the people, the Chief Executive is, and it is entirely appropriate for this political branch of the Government to make such policy choices - resolving the competing interests which Congress itself either inadvertently did not resolve, or intentionally left to be resolved by the agency charged with the administration of the statute in light of everyday realities.
When a challenge to an agency construction of a statutory provision, fairly conceptualized, really centers on the wisdom of the agency's policy, rather than whether it is a reasonable choice within a gap left open by Congress, the challenge must fail. In such a case, federal judges - who have no constituency - have a duty to respect legitimate policy choices made by those who do. The responsibilities for assessing the wisdom of such policy choices and resolving the struggle between competing views of the public interest are not judicial ones.
Id. at 865-66.
In Christensen v Harris County, 529 US 576 (2000), the Supreme Court discussed which agency actions should not receive Chevron deference:
Here, however, we confront an interpretation contained in an opinion letter, not one arrived at after, for example, a formal adjudication or notice-and-comment rulemaking. Interpretations such as those in opinion letters - like interpretations contained in policy statements, agency manuals, and enforcement guidelines, all of which lack the force of law - do not warrant Chevron-style deference.
Id. at 587. The Supreme Court indicated that "interpretations contained in formats such as opinion letters are ‘entitled to respect' under our decision in Skidmore v Swift & Co, 323 US 134 (1944), but only to the extent that those interpretations have the ‘power to persuade.'" Christensen, 529 US at 587.
In United States v Mead Corp, 533 US 218 (2001), the Supreme Court further examined the instances when Chevron deference would apply:
We hold that administrative implementation of a particular statutory provision qualifies for Chevron deference when it appears that Congress delegated authority to the agency generally to make rules carrying the force of law, and that the agency interpretation claiming deference was promulgated in the exercise of that authority. Delegation of such authority may be shown in a variety of ways, as by an agency's power to engage in adjudication or notice-and-comment rulemaking, or by some other indication of a comparable congressional intent.
Id. at 226-27.
Christensen and Mead signal the revival of Skidmore deference. In Skidmore v Swift & Co, 323 US 134 (1944), the Supreme Court discussed the standard of review when an agency was not engaged in notice-and-comment rulemaking or formal adjudication:
We consider that the rulings, interpretations and opinions of the Administrator under this Act, while not controlling upon the courts by reason of their authority, do constitute a body of experience and informed judgment to which courts and litigants may properly resort for guidance. The weight of such a judgment in a particular case will depend upon the thoroughness evident in its consideration, the validity of its reasoning, its consistency with earlier and later pronouncements, and all those factors which give it power to persuade, if lacking power to control.
Id. at 140.
Professor Pierce describes what is meant by Skidmore deference in his administrative law treatise:
The deference to be accorded an interpretative rule under Skidmore is much weaker than Chevron deference . . . because it has an entirely different source. Skidmore deference is not based on the institutional legitimacy of the agency pronouncement; an interpretive rule [i.e. a general agency pronouncement that is neither from notice-and-comment rulemaking nor formal adjudication] cannot have binding effect because Congress has not authorized any agency to issue an interpretive rule with binding effect. Skidmore deference is based solely on common sense. A court should consider adopting the position taken in an agency interpretative rule because there are reasons to believe that the agency positions are often wise and correct.
1 Pierce, Administrative Law Treatise (4th ed. 2002)
§ 6.4, p 334.
 In essence, the intelligible-principle doctrine requires just a vague indication of congressional intent, and the agency in question is then allowed extremely broad discretion in creating regulations on the subject of the delegation.
 A simple Westlaw search for articles citing Chevron in the Lawrev-Pro database led to nearly 4,000 entries.
 As will become clear below, Skidmore deference is a misnomer since it means the agency view is not binding and is only potentially persuasive to the courts.
 In his administrative law treatise, Professor Richard J. Pierce, Jr., indicates that agencies sometimes game the system by avoiding judicial review and yet still influencing the regulated community's behavior:
Sometimes ambiguities in agency statements are created intentionally for strategic purposes. An agency might want to issue a statement that has binding effect without following the notice and comment procedures mandated for legislative rulemaking and without subjecting its statement to the kind of "searching and careful" judicial review courts typically apply to legislative rules. To further these illegitimate strategy goals, an agency might intentionally use ambiguous or inconsistent language in the hope that its regulates will give its statements binding effect while the courts will characterize the statement as an unreviewable general statement of policy exempt from notice and comment procedures.
1 Pierce, Administrative Law Treatise (4th ed 2002) § 6.3, p 317.