Belden Mining Company (Belden) (defendant) contracted to deliver ore to Billing & Eilers. The price for each delivery was to be determined after the parties’ examination of each specific delivery. At times, an umpire would decide a fair price. Once a price was determined, Billing & Eilers would pay Belden. Thus, there was occasionally a significant time gap between delivery and payment. Belden had no security for its interest during this period. Billing & Eilers dissolved and assigned the contract to Mr. Billing. Belden did not object to this assignment. Thereafter, Mr. Billing assigned the contract to Arkansas Valley Smelting Company (Arkansas Valley) (plaintiff). Belden did not approve this assignment to Arkansas Valley and refused to perform. Arkansas Valley sued Belden. The lower court ruled in favor of Belden. The United States Supreme Court granted certiorari.