e.g., Withrow v. Larkin, 421 U.S. 35, 54, 95 S.Ct. 1456, 43 L.Ed.2d 712 (1975) (permitting such a combination of functions); FTC v. Cement Institute, 333 U.S. 683, 702, 68 S.Ct. 793, 92 L.Ed. 1010 (1948) (same). That sort of mixing is endemic in agencies, and has been "since the beginning of the Republic." Arlington, 569 U.S. at 304-305, n. 4, 133 S.Ct. 1863. It does not violate the separation of powers, we have explained, because even when agency "activities take 'legislative' and 'judicial' forms," they continue to be "exercises of[ ] the 'executive Power' "-or otherwise said, ways of executing a statutory plan. Ibid. (quoting U. S. Const., Art. II, § 1, cl. 1 ). So Kisor's last argument to dispatch Auer deference fails as roundly as the rest.
B
If all that were not enough, stare decisis cuts strongly against Kisor's position. "Overruling precedent is never a small matter." Kimble v. Marvel Entertainment, LLC, 576 U. S. ----, ----, 135 S.Ct. 2401, 2409, 192 L.Ed.2d 463 (2015). Adherence to precedent is "a foundation stone of the rule of law." Michigan v. Bay Mills Indian Community, 572 U.S. 782, 798, 134 S.Ct. 2024, 188 L.Ed.2d 1071 (2014). "[I]t promotes the evenhanded, predictable, and consistent development of legal principles, fosters reliance on judicial decisions, and contributes to the actual and perceived integrity of the judicial process." Payne v. Tennessee, 501 U.S. 808, 827, 111 S.Ct. 2597, 115 L.Ed.2d 720 (1991). To be sure, stare decisis is "not an inexorable command." Id., at 828, 111 S.Ct. 2597. But any departure from the doctrine demands "special justification"-something more than "an argument that the precedent was wrongly decided." Halliburton Co. v. Erica P. John Fund, Inc., 573 U.S. 258, 266, 134 S.Ct. 2398, 189 L.Ed.2d 339 (2014).
And that is even more than usually so in the circumstances here. First, Kisor asks us to overrule not a single case, but a "long line of precedents"-each one reaffirming the rest and going back 75 years or more. Bay Mills, 572 U.S. at 798, 134 S.Ct. 2024 ; see nn. 2, 3, supra. This Court alone has applied Auer or Seminole Rock in dozens of cases, and lower courts have done so thousands of times. Deference to reasonable agency interpretations of ambiguous rules pervades the whole corpus of administrative law. Second, because that is so, abandoning Auer deference would cast doubt on many settled constructions of rules. As Kisor acknowledged at oral argument, a decision in his favor would allow relitigation of any decision based on Auer, forcing courts to "wrestle [with] whether or not Auer " had actually made a difference. Tr. of Oral Arg. 30; see id., at 47 (Solicitor General agreeing that "every single regulation that's currently on the books whose interpretation has been established under Seminole Rock now [would have] to be relitigated anew"). It is the rare overruling that introduces so much instability into so many areas of law, all in one blow.
And third, even if we are wrong about Auer, "Congress remains free to alter what we have done." Patterson v. McLean Credit Union, 491 U.S. 164, 172-173, 109 S.Ct. 2363, 105 L.Ed.2d 132 (1989) (stating that when that is so, "[c]onsiderations of stare decisis have special force"). In a constitutional case, only we can correct our error. But that is not so here. Our deference decisions are "balls tossed into Congress's court, for acceptance or not as that branch elects." Kimble, 576 U. S., at ----, 135 S.Ct., at 2409. And so far, at least, Congress has chosen acceptance. It could amend the APA or any specific statute to require the sort of de novo review of regulatory interpretations