and at oral argument EPA was emphatic: it did not waive its non-merits, threshold defense that Petitioners are barred from challenging the wastewater limits because they failed to object to them during the notice and comment period. Resp. Br. 33-35; Oral Arg. Rec. at 30:00-32:00; 40:30-45:00. EPA contended that, if the court found the issue to be properly before the court, then and only then would EPA “not oppose” a stay or vacatur of the wastewater limits. Resp. Br. 35. EPA’s consent is not alone a sufficient basis for us to stay or vacate a rule. The court is not bound to accept, and indeed generally should not uncritically accept, an agency’s concession of a significant merits issue. Cf. Bowen v. Georgetown Univ. Hosp., 488 U.S. 204, 212-13, 109 S.Ct. 468, 102 L.Ed.2d 493 (1988) (<HOLDING>). The risk is that an agency could circumvent
holding that courts must defer to executive branch regulations implementing statutes so long as agencys regulation is based on a permissible construction of the statute holding that courts should defer to agencys interpretation of its own regulations if not plainly erroneous or inconsistent with the regulation holding that courts will not defer to an agencys litigating position where it contradicts the agencys prior regulations rulings or administrative practice holding that the directors litigating position was not entitled to chevron deference but did warrant skidmore respect on certain issues where the arguments were persuasive and the agencys manual and practice had for some time consistently advanced a reasonable position holding that judicial review of an administrative agencys decision is limited solely to whether given the relevant standard and facts the agencys decision was arbitrary illegal capricious or unreasonable