What is the scope of our review of a district court's decision to approve a class action settlement?

Our review of the district court's decision to approve a class action settlement is extremely limited. As we explained in Officers for Justice v. Civil Service Comm'n of San Francisco, 688 F.2d 615 (9th Cir.1982) (Officers for Justice ), cert. denied, 459 U.S. 1217, 103 S.Ct. 1219, 75 L.Ed.2d 456 (1983), "[t]he initial decision to approve or reject a settlement proposal is committed to the sound discretion of the trial judge." Id. at 625. "We are not to substitute our notions of fairness for those of the district judge and the parties to the agreement. Consequently, we will reverse only upon a showing that the district court's decision was a clear abuse of discretion." Id. at 626 (internal citations omitted).