Ricoh Co., Ltd. (Ricoh) (plaintiff) held patents relating to recordable and rewritable optical-disc technology. The ‘552 patent covered a method for controlling how quickly a disc drive could spin an optical disc. The ‘755 patent covered methods of writing data to optical discs in multiple sessions. Quanta Computer Inc. (QCI) manufactured notebook computers and sold the computers to other companies for retail marketing. QCI partially owned Quanta Storage, Inc. (QSI), which manufactured optical disc drives and sold the drives to United States customers, including NU Technologies (defendant), for ultimate retail sale. QCI also partially owned notebook-computer repairer Quanta Computer USA, Inc. (QCA, and collectively with QCI and QSI, Quanta) (defendants). Ricoh sued Quanta and NU in federal court, alleging that Quanta and NU had directly infringed the ‘552 and ‘755 patents under 35 U.S.C. § 271(a) by selling or offering for sale software that caused disc drives to perform Ricoh’s patented methods. Ricoh also asserted that Quanta contributorily infringed the ’552 and ‘755 patents under 35 U.S.C. § 271(c) by selling optical disc drives that contained components used only to perform the patented disc-recording methods. The district court granted summary judgment for Quanta and NU, finding, among other things, that (1) Quanta had not directly infringed the ‘552 and ‘755 patents because Quanta neither sold nor offered to sell the patented methods, and (2) Quanta had not contributorily infringed the ‘552 and ’755 patents because the devices sold by Quanta had the substantial noninfringing use of reading discs. Ricoh appealed.