	Background

Congress has created numerous administrative agencies to implement and enforce delegated regulatory authority. As this report explains, when a court reviews an agency's interpretation of a statute it is charged with administering, the court will generally apply the two-step framework outlined by the Supreme Court in Chevron U.S.A., Inc. v. Natural Resources Defense Council . This report discusses the Chevron decision, explains the circumstances in which the Chevron doctrine applies, explores how courts apply the two steps of Chevron , and highlights some criticisms of the doctrine, with an eye towards the potential future of Chevron deference. 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. First, the Court invoked a judicial presumption about legislative intent, which has subsequently become one of the leading justifications for deferring to agencies under Chevron : 
If Congress has explicitly left a gap for the agency to fill, there is an express delegation of authority to the agency to elucidate a specific provision of the statute by regulation.... As an initial matter, the Chevron framework of review is limited to agencies' interpretations of statutes they administer. In City of Arlington v. FCC , the Court rejected the contention that Chevron deference should not apply to an agency's "interpretation of a statutory ambiguity that concerns the scope of the agency's statutory authority," reasoning that "there is no difference, insofar as the validity of agency action is concerned, between an agency's exceeding the scope of its authority (its 'jurisdiction') and its exceeding authorized application of authority that it unquestionably has." Instead, once the "preconditions to deference under Chevron are [otherwise] satisfied," the Court should proceed to the Chevron two-step framework and determine if the agency has reasonably interpreted the parameters of its statutory authority. Step one requires a court to determine whether Congress "directly addressed the precise question at issue." Some courts may also employ the traditional tools of statutory construction at Chevron 's second step. Chevron is a judicially created doctrine that rests, in part, upon an assumption made by courts about congressional intent: that where a statute is silent or ambiguous, Congress would have wanted an agency, rather than a court, to fill in the gap. Accordingly, Congress can determine whether a court will apply Chevron review to an agency interpretation.
When Congress delegates regulatory functions to an administrative agency, that agency's ability to act is governed by the statutes that authorize it to carry out these delegated tasks. Accordingly, in the course of its work, an agency must interpret these statutory authorizations to determine what it is required to do and to ascertain the limits of its authority. The scope of agencies' statutory authority is sometimes tested through litigation. When courts review challenges to agency actions, they give special consideration to agencies' interpretations of the statutes they administer. Judicial review of such interpretations is governed by the two-step framework set forth in Chevron U.S.A. Inc., v. Natural Resources Defense Council.
The Chevron framework of review usually applies if Congress has given an agency the general authority to make rules with the force of law. If Chevron applies, a court asks at step one whether Congress directly addressed the precise issue before the court, using traditional tools of statutory construction. If the statute is clear on its face, the court must effectuate Congress's stated intent. However, if the court concludes instead that a statute is silent or ambiguous with respect to the specific issue, the court proceeds to Chevron's second step. At step two, courts defer to an agency's reasonable interpretation of the statute.
Application of the Chevron doctrine in practice has become increasingly complex. Courts and scholars alike debate which types of agency interpretations are entitled to Chevron deference, what interpretive tools courts should use to determine whether a statute is clear or ambiguous, and how closely courts should scrutinize agency interpretations for reasonableness. A number of judges and legal commentators have even questioned whether Chevron should be overruled entirely. Moreover, Chevron is a judicially created doctrine that rests in large part upon a presumption about legislative intent, and Congress could modify the courts' use of the doctrine by displacing this underlying presumption.
This report discusses the Chevron decision, explains the circumstances in which the Chevron doctrine applies, explores how courts apply the two steps of Chevron, and highlights some criticisms of the doctrine, with an eye towards the potential future of Chevron deference.