f Contracts § 69(1)(a). *19 William F. Lee with whom Robert D. Keefe, Stephen A. Jonas, Mark D. Selwyn, Hale and Don LLP, Richard G. Taranto, and Farr & Taranto were on brief, for ap- pellant. James E. Arnold, Trial Attorney, United States Department of Justice, with whom Michael K. Loucks, Chief, Health C