Prior Invention Requires Proof of Reduction to Practice

Z4 Technologies, Inc., v. Microsoft Corporation, [2006-1638](November 16, 2007)[LINN, Lourie, Bucklo] The Federal Circuit affirmed the district court's denial of Microsoft’s motion for judgment as a matter of law ("JMOL") following a jury trial in which the jury found that Microsoft had infringed z4's U.S. Patents Nos. 6,044,471 and 6,785,825.
SIGNIFICANCE: A patent challenger is not entitled to an instruction that the presumption of validity is easier to overcome with prior art not considered by the PTO.
BRIEF: While Microsoft persuaded the Federal Circuit that the construction of "USER" was incorrect, the Federal Circuit nonetheless found sufficient evidence to support the jury verdict of infringement. On validity, Microsoft argued that it was the prior inventor, which required Microsoft to establish an earlier reduction to practice. In order to establish an actual reduction to practice, the inventor must prove that: (1) he constructed an embodiment or performed a process that met all the limitations and (2) he determined that the invention would work for its intended purpose. However, because of conflicting testimony about the effectiveness of Microsoft's earlier product, the Federal Circuit found sufficient evidence to support a jury verdict that Microsoft had not reduced the invention to practice. The Federal Circuit also found no error in the district court's refusal to instruct the jury that the presumption of validity is easier to overcome when prior art was not considered by the Patent and Trademark Office.