SUMMARY ORDER

Defendants Knolls Atomic Power Laboratory, Lockheed Martin, and John J. Freeh (“defendants”) appeal the judgment of the district court reinstating a prior jury verdict in plaintiffs’ favor. Defendants argue that the district court committed clear error in holding that they waived the defense based on reasonable factors other than age (“RFOA”), and that the waiver was not properly excused; they also argue that, if we vacate the waiver and excuse holdings, we should order that judgment be granted in their favor as a matter of law. We assume the parties’ familiarity with the underlying facts, the procedural history, and the issues presented for review.

Vacatur of the judgment is required by adherence to the “mandate rule,” which “compels compliance on remand with the dictates of the superior court and forecloses relitigation of issues expressly or impliedly decided by the appellate court.” United States v. Ben Zvi, 242 F.3d 89, 95 (2d Cir. 2001) (internal quotation marks omitted) (emphasis in original); see also In re Sanford Fork & Tool Co., 160 U.S. 247, 255, 259, 16 S.Ct. 291, 40 L.Ed. 414 (1895). To determine whether a particular issue “remains open for reconsideration on remand, [a] court should look to both the specific dictates of the remand order as well as the broader spirit of the mandate.” Ben Zvi, 242 F.3d at 95 (internal quotation marks omitted). “[W]e must always look to the opinion to interpret the mandate.” FTC v. Standard Educ. Soc’y, 148 F.2d 931, 932 (2d Cir. 1945).

In an earlier decision in this case, the United States Supreme Court explained that “the only thing at stake ... is the gap between production and persuasion” and that this Court “showed no hesitation in finding that Knolls prevailed on the RFOA defense, though the court expressed its conclusion in terms of Meaeham’s failure to meet the burden of persuasion. Whether the outcome should be any different when the burden is properly placed on the employer is best left to that court in the first instance.” See Meacham v. Knolls Atomic Power Lab., 554 U.S. 84, ---, 128 S.Ct. 2395, 2406, 171 L.Ed.2d 283 (2008) (“Meacham SC II”); see also Meacham v. Knolls Atomic Power Lab., 461 F.3d 134, 144 (2d Cir. 2006), vacated by Meacham SC II, 128 S.Ct. at 2407. Waiver principles are analytically antecedent to an analysis on the merits; we therefore read the Supreme Court’s opinion as impliedly but necessarily rejecting plaintiffs’ waiver argument.

Our conclusion in this regard finds additional support from the fact that plaintiffs argued forfeiture and abandonment in their brief to the Supreme Court and waiver of the defense at oral argument before the Supreme Court. Brief for the Petitioners at 51-52, Meacham SC II, Tr. of *236 Oral Argument at 53, Meacham SC II. The Court, therefore, was squarely presented with plaintiffs’ waiver argument, and a natural reading of Meacham SC II suggests that it was rejected.

Our summary order issued in this case, Meacham v. Knolls Atomic Power Lab., 305 Fed.Appx. 748 (2d Cir. 2009) (summary order), requires no different result. That order does not constitute a finding regarding waiver, nor, having re-examined the issue in light of the arguments presented in this appeal, does it preclude us now from determining that the mandate rule forecloses reconsideration of the waiver issue.

We therefore remand this case to the district court with instructions to hold a new trial and to allow for whatever discovery is necessary for the parties fairly to litigate the issues regarding liability under the law as it currently stands. The uncertainty and multiple changes in the governing law have complicated the issues in this case to such an extent that neither party is entitled to judgment as a matter of law, either on the merits or on procedural grounds.

We hereby VACATE the judgment of the district court and REMAND for a new trial on the liability issue only.