But buried in the opinion was a new and deceptively simple test. First, courts must consider whether the relevant statutory text answers the question at hand. If so, courts should follow Congress’s command. If, on the other hand, the reviewing court finds the statute ambiguous, it must defer to the agency’s interpretation, provided it is reasonable. Before long, this test was dubbed a doctrine, and the rest is history.

For most of the past 40 years, the Chevron doctrine has defined the parameters of judicial review of agency action, and Chevron v. NRDC is one of the Court’s most cited administrative law decisions of all time. Yet a growing number of jurists and commentators have begun questioning the doctrine and how it is applied in federal courts.

Critics maintain Chevron encourages courts to abdicate their obligation to say what the law is and makes it too easy for agencies to make policy decisions that are properly left to the legislature. In one of his last opinions for the Court, Justice Anthony Kennedy lamented how the doctrine encouraged “reflexive deference” by lower courts and suggested the Court “reconsider the premises that underlie Chevron and how courts have implemented” it. Kennedy’s replacement, Justice Neil Gorsuch, would agree. Before he was appointed, then‐​Judge Gorsuch labeled Chevron a “behemoth” that “permit[s] executive bureaucracies to swallow huge amounts of core judicial and legislative power and concentrate federal power in a way that seems more than a little difficult to square with the Constitution of the framers’ design.”

In his recent book The Chevron Doctrine: Its Rise and Fall, and the Future of the Administrative State, Columbia law professor Thomas Merrill expertly assesses the doctrine and where it has gone wrong. The book provides a rich and insightful account of how the Chevron doctrine came to be and how it came to be so controversial. Merrill excavates the pressures Chevron places on rule‐​of‐​law values. He also examines how the doctrine could be reformulated in a way that safeguards reliance interests and legislative control of agency action without requiring courts to disregard agency expertise and insight across the board.

Remaking administrative law / Prior to Chevron, courts exercised de novo review of agency interpretations of federal statutes, meaning they examined the issue without deferring to some previous governmental decision. But the courts also gave due regard to an agency’s longstanding and consistent view, particularly if it was first offered contemporaneously with the relevant statute’s adoption. Consistent with the 1946 Administrative Procedure Act’s instruction that courts “shall decide all relevant questions of law,” courts exercised “independent judgment” in determining how much weight to give agency interpretations, though what that meant could vary from case to case. Courts accepted that Congress sometimes expects agencies to fill in the interstices of complex statutes or resolve minor ambiguities, while recognizing the broad sweep of agency authority had to be identified by judges rather than administrators.

But as Merrill writes, “Then came the Chevron decision.”

As noted above, no one at the time thought Chevron presented “any question about the court–agency relationship in resolving questions of statutory interpretation.” Rather, all understood the case to be about how the Clean Air Act was to be implemented. Under that law, “stationary sources” of regulated pollutants were required to obtain permits when making facility changes that could increase emissions. The question was what constitutes a source: each smokestack or opening from which pollutants could emanate, or the facility as a whole? In the case of something like an oil refinery, this difference could be quite substantial, hence the controversy. While the question was clear, neither the text of the act nor the associated legislative history provided an answer.

Environmentalist groups preferred the former interpretation, as had Jimmy Carter’s administration, because it would place more pressure on firms to reduce emissions. Ronald Reagan’s administration preferred the latter approach because it would ease regulatory burdens. Accordingly, Reagan’s Environmental Protection Agency promulgated regulations adopting the plant‐​wide definition of “source,” and environmentalist groups sued.

The U.S. Court of Appeals for the D.C. Circuit, in an opinion by then–Judge Ruth Bader Ginsburg, rejected the EPA approach. While acknowledging that the text of the law was unclear, she argued that the more stringent interpretation was warranted so as to effectuate the broader goals of the act. The Supreme Court, however, concluded the case presented what was really a policy question—whether to adopt a more stringent or a more flexible regulatory policy—and policy questions of that sort were properly left to the administrative agency charged with implementing the law, in this case the EPA.

That Chevron would remake administrative law was not clear when the opinion was first issued. “If one reads the entire opinion from beginning to end, one discovers a relatively conventional exercise in judicial review,” recounts Merrill. The exception was a brief passage setting forth what would become known as the Chevron doctrine, a mere two paragraphs in a 27‐​page opinion. These two paragraphs “are endlessly quoted or paraphrased in thousands of decisions,” yet “do not appear to reflect the standard of review that Justice Stevens actually applied in the decision itself.” Nor did the Court announce it was making any change to existing doctrine on judicial review of agency action.

The recognition that these two paragraphs announced a new test for courts to apply was left to the D.C. Circuit, the federal appellate court in which a disproportionate percentage of challenges to federal agency actions are heard. It was there that lower court judges, intent on following the instructions emanating from One First Street, embraced Justice Stevens’ two paragraphs as dictating courts’ “proper task in reviewing an administrative construction of a statute that the agency administers.”

As Merrill explains, the Chevron doctrine was embraced because it made things easier for both the judicial and executive branches. “Lower‐​court judges were drawn to the Chevron doctrine because it is refreshingly simple in contrast to the complex matrix of factors that prevailed in the pre‐Chevron era.” No less significantly, “the Chevron doctrine was regarded as a godsend by executive branch lawyers charged with writing briefs defending agency interpretations of law.” If the relevant statutory language was not clear, agency lawyers could rely upon Chevron to defend their “reasonable” interpretations.

Chevron’s early defenders, Justice Antonin Scalia in particular, celebrated the doctrine as a way to take policy decisions out of the hands of judges and commit them to the executive branch. Yet it is not clear that is quite what Chevron accomplished. As Merrill notes, “The Chevron doctrine, in practice, does little to constrain judicial willfulness.” In no small part, this is because neither Chevron nor subsequent decisions made clear how judges should determine when a statute is sufficiently ambiguous to require that court defer to agencies. Thus, in practice, Chevron “translates into … reduced decisional costs for judges and more judicial discretion.”

While the language of judicial opinions changed, it’s less clear many results did. The rate at which courts accepted agency interpretations appears to have increased only a small amount, but the universe of agency actions under review may have shifted under the new rules. The availability of Chevron deference appears to have encouraged agencies to be more aggressive in interpreting the statutes they administer, unearthing new regulatory authority in old statutes when Congress refuses (or simply cannot be bothered) to enact statutory reforms. In this way the doctrine “facilitated the transfer of power from Congress to the administrative state.”

It is this effective transfer of power that fuels Chevron’s critics. The doctrine emboldens agencies to stretch the bounds of statutory authorizations, and further encourages administrators to embark on new policy initiatives by exploiting the ambiguity of existing statutory delegations instead of turning to Congress. The doctrine has the virtue of providing a deceptively simple test that appears easy to administer. Yet the test is not as simple to apply as it might appear, and it has made it too easy for agencies to revise regulatory requirements and too difficult for courts to police the boundaries of agency authority. Over time, it has become clear that “the doctrine failed to account for settled expectations created by agency interpretations, and failed to acknowledge the importance of a contextual examination of the scope of the agency’s delegated authority.”

Revising Chevron / Merrill’s prescription is more to mend Chevron than to end it, though some might view his proposed modifications as a lethal prescription. In his view, courts should “try to figure out where agencies have a comparative advantage and where courts have a comparative advantage, and to assign roles to each institution that reflect how each can make a positive ‘marginal’ contribution to the process of saying what the law is.” Judicial review of agency interpretations of law should not only encourage agencies to make sound interpretive choices and channel discretionary policy choices toward politically accountable institutions. It should also reinforce constitutional and rule‐​of‐​law values to protect settled expectations and ensure due process. As he emphasizes, the Constitution establishes a structure of “legislative supremacy” in that all law‐​making power is vested in the legislature, and administrative agencies only have the power that Congress has chosen to delegate to them (usually, though not necessarily, with the president’s concurrence). Accordingly, the real question in Chevron cases should not be “Is this language ambiguous?” but rather “Is there persuasive evidence that Congress actually delegated authority to the agency to resolve this particular question?”

While no change has been explicit, it appears the Court is beginning to think more deeply about Chevron’s premises and how deference should be constrained along the lines Merrill suggests. This is but one reason The Chevron Doctrine is a particularly timely book. While the justices seem reluctant to require courts to resolve each and every challenge to agency action on purely textual grounds, it seems to be sending the message that Chevron should only apply when the relevant statutory provisions are genuinely ambiguous, not merely when they are complicated or difficult to parse, and only when it is clear Congress delegated such policymaking authority to the agency.

Despite the criticisms, lower courts continue to rely upon Chevron with regularity. The same cannot be said at One First Street. Chevron has not been relied upon by a majority of the Court to decide a case since 2016. In this regard, Chevron has already become something of “the Lord Voldemort of administrative law,” as one appellate judge commented, because the justices no longer seem willing to speak its name. And while the justices have not yet opted to reconsider Chevron, recent decisions (such as West Virginia v. EPA) have narrowed the domain in which Chevron applies.

In 1984, Chevron v. NRDC remade administrative law. Before the decision turns 40, the Supreme Court may remake Chevron. If so, Merrill’s book may have helped show the Court how to do it.