United States: Actual Reduction Practice Requires Proof of Inventor’s Appreciation that the Invention Would Work

The U.S. Court of Appeals for the Federal Circuit has now held that a district court must define an invention in dispute prior to determining issues relating to conception and reduction to practice, and that for an actual reduction to occur, it must be established that the inventor appreciated that the invention will work for its intended purpose. Slip Track Systems, Inc. v. Metal Lite, Inc., Case No. 01-1187 (Fed. Cir. Sept. 11, 2002).

Slip Track Systems, Inc. ("Slip Track"), owner of U.S. Patent No. 5,127,760 ("the Slip Track Patent"), instituted an interference proceedings between its patent and U.S. Patent No. 5,127,203 owned by Metal Lite, Inc. ("the Metal Lite Patent" and "Metal Lite", respectively), in district court. Both patents are directed to an earthquake resistant wallboard structure that permits a wallboard to slide vertically with respect to the supporting wall studs. The parties agreed that the claims of their respective patents interfered.

The Slip Track patent had a filing date later than that of the Metal Lite patent, thus placing the burden on Slip Track to establish priority. Slip Track presented evidence of conception prior to the Metal Lite filing date. Slip Track also contended that it reduced the invention to practice when it made a cardboard model of the invention and presented expert testimony asserting that one of skill on the art would understand that the cardboard model demonstrated that the invention, when made of wallboard, would work. Metal Lite presented no rebuttal expert, but asserted that the cardboard model could not establish a reduction to practice because it was made of a different material than that intended for use as part of the invention. The district court, applying a "clear and convincing" standard, awarded priority to Metal Lite, finding that Slip Track conceived the invention prior to Metal Lite’s filing date, but did not reduce the invention to practice.

The Federal Circuit vacated the award of priority, initially noting that a "preponderance of the evidence" standard, rather than a "clear and convincing evidence" standard, should be used for all priority determinations. The Federal Circuit also held that, prior to determining issues relating to conception and actual reduction to practice, the district court must define the invention in dispute, in a manner similar to the practice of defining a "count" in U.S. Patent and Trademark Office interference proceedings. While noting that a reduction to practice requires that the inventor prove that he constructed an embodiment or performed a process that met all the limitations of the claim, the Federal Circuit held that the invention in dispute did not require the presence of wallboard, and that the cardboard model satisfied all of the limitations needed for an actual reduction to practice. The Federal Circuit pointed out that neither a lack of testing nor a change in materials necessarily defeats a showing of an actual reduction to practice, explaining that testing and the use of the different materials are simply relevant factors to consider in making a determination as to whether the inventor could have determined that the invention would work for its intended purpose. The case was remanded to the district court for fact-finding as to whether the inventor determined the invention would work for its intended purpose based on the cardboard model.