How have the courts interpreted the statute of limitations in a case?

An important issue in the case was whether the five-year statute of limitations barred prosecution. Because the government's information was filed on December 12, 1988, the jury was instructed that it had to find that the conspiracy was in existence after December 12, 1983. Appellants contend that the district court confused the jury through the use of contradictory instructions on this issue and failed to include a mens rea element in the last overt act instruction. Since a proper objection to these instructions was not made below, we review for plain error. United States v. Ramos, 861 F.2d 228, 230 (9th Cir.1988). We will reverse for plain error only in exceptional circumstances; the error must have affected substantial rights, and it must be highly probable that the error materially affected the verdict. Id.