The U.S. Court of Appeals for the Federal Circuit held that it was improper for the district court to modify its claim construction after the instruction of the jury as to the meaning of claim terms. The Court also held that an in-court demonstration of a prior art device was sufficient corroboration of oral evidence to support a finding of invalidity. Hewlett-Packard Co. v. Mustek Systems, Inc., Case Nos. 02-1372, -1395, -1465 (Fed. Cir. August 7, 2003)
The two patents in suit involve optical scanner technology, in which images and text from a document are converted into electronic data. The jury was instructed that a claimed "scan speed indicating means" required a user selectable scan speed device. Neither party objected to the instruction. At trial, the jury found that Mustek literally infringed. The jury did not address infringement under the doctrine of equivalents.
