The Supreme Court dealt a stealth blow to North Carolina—and every other state or school district gripped by anti-trans bathroom panic—when it declined to hear United Student Aid Funds v. Bible on Monday.

Bible seemingly has nothing to do with bathroom equality for transgender people: It is a case about the interpretation of Department of Education (DOE) regulations related to the repayment of student debt. But the case reaffirmed that federal agencies are given wide latitude when it comes to implementing their own regulations.

There’s a decades-old legal principle that the Obama administration has relied on to expand the protections of Title IX of the United States Education Amendments of 1972—which prohibits sex discrimination in schools that receive federal funds—so that transgender students can use restroom and locker facilities that align with their gender identity.

That principle is one of judicial deference to agency interpretation. In two key cases—Auer v. Robbins in 1997 and Bowles v. Seminole Rock & Sand Co. in 1945—the Supreme Court said that courts are required to defer to a federal agency’s interpretation of its implementing regulations as long as that interpretation is not “plainly erroneous” or inconsistent with the regulation itself.

That means that when it comes to interpreting Title IX, the Department of Education is well within its right to write its own regulations and to interpret those regulations as it sees fit, as long as the courts don’t deem its interpretation as obviously wrong.

This principle of judicial deference to agency interpretation, sometimes referred to as the Auer/Seminole Rock doctrine, is key to the Obama administration’s fight for justice for transgender students. If the Department of Education may properly interpret Title IX and the regulations implementing it as requiring that “a school generally must treat transgender students consistent with their gender identity,” then schools like the University of North Carolina, or those in Virginia’s Gloucester County School District or Illinois’ Palatine-Schaumburg High School District 211 must not discriminate against their students when it comes to bathroom access, lest they risk their federal funding. Indeed, in her letter to Gov. Pat McCrory (R) earlier this month regarding North Carolina’s anti-trans HB 2, Deputy Assistant Attorney General Vanita Gupta specifically noted that “the Department of Education’s guidance that educational institutions ‘generally must treat transgender students consistent with their gender identity’ is entitled to ‘controlling weight’ under Auer v. Robbins.” 

This principle has also vexed conservative commentators and legal scholars for decades. They believe that permitting an agency to make its own regulations and interpret them violates basic principles of federalism and separation of power. In the wake of the Obama administration’s insistence that transgender students, like cisgender ones, should be permitted the personal dignity of using a bathroom that aligns with their gender identity, conservatives have been chomping at the bit for a case that would present just the right circumstances for the Supreme Court to revisit the principle.

United States Student Aid Funds v. Bible, a case involving one young woman’s struggle to repay her student debt, presented just such a case. Bryana Bible had sued USA Funds, alleging that the guaranty agency had demanded that she pay collection costs that weren’t authorized by the Higher Education Act (HEA) or its implementing regulations.

USA Funds noted that the HEA permitted assessing “reasonable collection costs.” Bible retorted that assessing costs against a first-time defaulter who had entered into a repayment agreement and had made every payment on time was not reasonable.

The Secretary of Education—who is in charge of interpreting the HEA and associated regulations—agreed with Bible, and the Seventh Circuit Court of Appeals noted that under the principle of judicial deference to an agency’s interpretation, the Secretary’s interpretation was controlling, as long as it was not plainly erroneous or contradicted by the HEA.

USA Funds filed a petition for writ of certiorari, and 15 states filed one amicus brief urging the Court to grant certiorari in order to “vindicate constitutional principles of federalism.”

And had Justice Antonin Scalia not died earlier this year, the Supreme Court might have.

Scalia authored the opinion in Auer v. Robbins, but as the amicus states pointed out in their brief, Scalia was one of four justices who had indicated a willingness to reconsider the Auer/Seminole Rock doctrine. Scalia himself wrote in 2011 in Talk America, Inc. v. Michigan Bell Tel. Co., “While I have in the past uncritically accepted that rule, I have become increasingly doubtful of its validity.”

In 2013, Chief Justice John Roberts expressed a willingness in Decker v. Northwest Environmental Defense Center to revisit the doctrine in “a case in which the issue is properly raised and argued.”

And in 2015 in Perez v. Mortgage Bankers Association, both Justice Samuel Alito and Justice Clarence Thomas noted in separate opinions that the doctrine should be reconsidered: Alito wrote that he “await[s] a case in which the validity of Seminole Rock may be explored through full briefing and argument,” while Thomas wrote that “[b]y my best lights, the entire line of precedent beginning with Seminole Rock raises serious constitutional questions and should be reconsidered in an appropriate case.”

Even Justice Anthony Kennedy expressed a willingness to tackle judicial deference: in 2006’s Gonzales v. Oregon, Kennedy found that deference might not be warranted if Congress did not delegate authority to the agency to make rules carrying the force of law.

All of this is to say that prior to Scalia’s death, there were four justices—and maybe a fifth—willing to take another look at judicial deference and potentially strip agencies of the authority to interpret their own implementing regulations.

Of course I have no way of knowing how close the Supreme Court came to granting certiorari in Bryana Bible’s case. Four votes are required for the Court to take a case, and the Court does not release a tally of votes. Justice Thomas did, however, pen a dissent in which he noted that “[a]ny 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.”

It’s true. They have. But neither Alito nor Roberts chose to join in Thomas’ dissent—why not, is anyone’s guess. Were Scalia alive, the Court likely would have had the four requisite votes to take the case. But he isn’t, so the Auer/Seminole Rock doctrine lives to see another day. And for now, so does the DOE’s interpretation that Title IX prohibits bathroom discrimination against transgender people.