The standard holding of the Supreme Court has been that such interpretations are entitled to deference. Justice Kennedy states the standard holding in the majority opinion in Decker v. Northwest Environmental Defense Center, ___ U.S. ___, 2013 U.S. LEXIS 2373 (3/20/13), here, a nontax case, as follows:
It is well established that an agency’s interpretation need not be the only possible reading of a regulation—or even the best one—to prevail. When an agency interprets its own regulation, the Court, as a general rule, defers to it “unless that interpretation is ‘plainly erroneous or inconsistent with the regulation.’”This deference is commonly referred to as "Seminole Rock" or "Auer" deference." See Bowles v. Seminole Rock & Sand Co., 325 U. S. 410 (1945); and Auer v. Robbins, 519 U. S. 452 (1997).
This broad deference to agency interpretations is not without its critics, even on the Supreme Court. In Decker, the issue surfaced again. Justice Scalia took the opportunity to swipe at it in detail in a dissent, and Chief Justice Roberts, with Justice Alito joining, in a concurring opinion, suggested that the issue might be reconsidered in another case. I first cover Chief Justice Roberts' short discussion and then cover Justice Scalia's full-throated -- is there any of way with Justice Scalia? -- criticism.