“Issues surrounding judicial deference to agency interpretations of their own regulations are distinct from those raised in connection with judicial deference to agency interpretations of statutes enacted by Congress,” Roberts wrote. “See Chevron U. S. A. Inc. v. Natural Resources Defense Council, Inc., 467 U. S. 837 (1984). I do not regard the Court’s decision today to touch upon the latter question.”

In effect, this is an open invitation for plaintiffs and their lawyers to challenge Chevron. It means that the prudential considerations leading Roberts to shy away from overturning Auer may not apply so strongly to Chevron. Exactly how or why that might be the case must await further elucidation, based on the particular facts in whatever case testing Chevron deference actually reaches the Supreme Court. Roberts’ mind is famously inscrutable and frustratingly changeable.

Still, it speaks volumes that, unbidden and rather gratuitously, Roberts included this reference to Chevron. It’s sort of like somebody turning down an invitation to a baseball game, but then, without even being offered, closes the conversation by saying how much fun it would be to go to a football game soon. Hint, hint.