Law360, New York (December 1, 2014, 6:04 PM EST) -- On Dec. 1, the U.S. Supreme Court heard oral arguments in Perez v. Mortgage Bankers Association, addressing the question whether an agency can revise a definitive interpretation of its own regulation without subjecting the revised interpretation to the Administrative Procedure Act's notice-and-comment rule-making procedures. At issue — and of great interest to the broader regulated community and followers of the Supreme Court's administrative law jurisprudence — is an almost-20-year-old D.C. Circuit precedent that discourages agency flip-flopping by requiring changes to interpretations of rules that are integral to the public's understanding of those rules to go through notice-and-comment rulemaking....