On Monday, the Supreme Court declined an invitation to reconsider whether federal courts should defer to agency interpretations of an agency’s own regulations. Specifically, the court denied certiorari in United Student Aid Funds v. Bible, in which the petitioners asked the court to reconsider so-called Auer and Seminole Rock deference.

The doctrine of Auer/Seminole Rock deference may be obscure — particularly to those who do not focus on administrative law — but it is quite significant, perhaps increasingly so. Under this doctrine, if an agency’s regulations are ambiguous, courts will defer to the promulgating agency’s reigning interpretation, even if the agency’s own view of the regulation has changed over time and the interpretation in question has never been subject to notice-and-comment or other regulatory procedures.

A recent case that illustrates the potential significance of Auer/Seminole Rock deference is G.G. v. Gloucester County School District.  In this case, the U.S. Court of Appeals for the 4th Circuit cited Auer/Seminole Rock deference to justify deferring to the Education Department’s Office of Civil Rights claim that regulations promulgated in the 1970s prohibiting discrimination “on the basis of sex” require local school districts to allow a transgender student access to facilities that correspond with the student’s gender identity. Note that instead of going through notice-and-comment procedures to issue regulations defining “sex,” for purposes of the relevant regulations, to include sexual identity, all the agency had to do was announce its interpretation in a letter.

Justice Clarence Thomas dissented from the court’s denial of certiorari in United Student Aid Funds. He wrote:

This petition asks the Court to overrule Auer v. Robbins, 519 U. S. 452 (1997), and Bowles v. Seminole Rock & Sand Co., 325 U. S. 410 (1945). For the reasons set forth in my opinion concurring in the judgment in Perez v. Mortgage Bankers Assn., 575 U. S. ___, ___ (2015), that question is worthy of review.

The doctrine of Seminole Rock deference (or, as it is sometimes called, Auer deference) permits courts to defer to an agency’s interpretation of its own regulation “unless that interpretation is plainly erroneous or inconsistent with the regulation.” Decker v. Northwest Environmental Defense Center, 568 U. S. ___, ___ (2013) (slip op., at 14) (internal quotation marks omitted). Courts will defer even when the agency’s interpretation is not “the only possible reading of a regulation—or even the best one.” Ibid.

Any reader of this Court’s opinions should think that the doctrine is on its last gasp. Members of this Court have repeatedly called for its reconsideration in an appropriate case. See Mortgage Bankers, 575 U. S., at ___–___ (ALITO, J., concurring) (slip op., at 1–2); id., at ___ (Scalia, J., concurring in judgment) (slip op., at 5); id., at ___ (THOMAS, J., concurring in judgment) (slip op., at 1–2); Decker, 568 U. S., at ___–___ (ROBERTS, C. J., concurring) (slip op., at 1–2); id., at ___–___ (Scalia, J., concurring in part and dissenting in part) (slip op., at 2–7); Talk America, Inc. v. Michigan Bell Telephone Co., 564 U. S. 50, 68–69 (2011) (Scalia, J., concurring); see also Christopher v. SmithKline Beecham Corp., 567 U. S. ___, ___–___ (2012) (slip op., at 10–14) (refusing to defer under Auer). And rightly so. The doctrine has metastasized, see Knudsen & Wildermuth, Unearthing the Lost History of Seminole Rock, 65 Emory L. J. 47, 54–68 (2015) (discussing Seminole Rock’s humble origins), and today “amounts to a transfer of the judge’s exercise of interpretive judgment to the agency,” Mortgage Bankers, supra, at ___ (slip op., at 13) (opinion of THOMAS, J.). “Enough is enough.” Decker, supra, at ___ (opinion of Scalia, J.) (slip op., at 1).

This case is emblematic of the failings of Seminole Rock deference. Here, the Court of Appeals for the Seventh Circuit deferred to the Department of Education’s interpretation of the regulatory scheme it enforces—an interpretation set forth in an amicus brief that the Department filed at the invitation of the Seventh Circuit. For the reasons stated in Judge Manion’s partial dissent, 799 F. 3d 633, 663–676 (2015), the Department’s interpretation is not only at odds with the regulatory scheme but also defies ordinary English. More broadly, by deferring to an agency’s litigating position under the guise of Seminole Rock, courts force regulated entities like petitioner here to “divine the agency’s interpretations in advance,” lest they “be held liable when the agency announces its interpretations for the first time” in litigation. Christopher, supra, at ___ (slip op., at 14). By enabling an agency to enact “vague rules” and then to invoke Seminole Rock to “do what it pleases” in later litigation, the agency (with the judicial branch as its co-conspirator) “frustrates the notice and predictability purposes of rulemaking, and promotes arbitrary government.” Talk America, Inc., supra, at 69 (Scalia, J., concurring).

This is the appropriate case in which to reevaluate Seminole Rock and Auer. But the Court chooses to sit idly by, content to let “[h]e who writes a law” also “adjudge its violation.” Decker, supra, at ___ (opinion of Scalia, J.) (slip op., at 7). I respectfully dissent from the denial of certiorari.

Although the court declined to reconsider Auer/Seminole Rock deference in this case, I suspect it’s only a matter of time before it agrees to reconsider this doctrine. Perhaps the court will do so when it again has nine justices. Indeed, perhaps there will be a cert petition in G.G. v. Gloucester County School District by then.