How have the courts interpreted the doctrine of waiver in a case of forfeiture?

United States v. Olano, 507 U.S. 725, 733, 113 S.Ct. 1770, 123 L.Ed.2d 508 (1993) ) (internal quotation marks and alterations omitted). This is not a case of forfeiture, where defense counsel simply failed to make a timely assertion of a [claimed] right. Id. at 845. Waiver occurred here because, despite having knowledge of the law, the defendants proposed or accepted what they now claim to be a flawed instruction. See id. That this election was knowing is underscored by the defendants' challenge to part A of the instruction versus their support for part B, the Hartford Fire formulation.