What is the test for determining whether a plaintiff's claim against the federal government can be asserted on an earlier appeal?

The government argues as an initial matter that the claim is barred by the mandate rule because it could have been asserted on his earlier appeals. We disagree. The mandate rule flows from the law-of-the-case doctrine. Under the rule, a district court is " 'barred from reconsidering or modifying any of its prior decisions that have been ruled on by the court of appeals.' " United States v. Minicone, 994 F.2d 86, 89 (2d Cir.1993) (quoting United States v. Uccio, 940 F.2d 753, 757 (2d Cir.1991)), cert. denied, 513 U.S. 940, 115 S.Ct. 344, 130 L.Ed.2d 300 (1994).