Under Section 102(g), in order to invalidate a patent claim on the ground of prior inventorship, an alleged infringer must prove either that it conceived of the invention first and was diligent in reducing it to practice or that it reduced its invention to practice before the critical date of the patent-at-issue.

The patent at issue is directed to a silicon carbide (“SiC”) wafer comprised of SiC material with specific low defect densities and the patent claims priority from a 1997 patent application. SiC is a semiconductor material that is used in high-temperature and high-power electronics. The alleged infringer sought to invalidate the patent on the basis of prior inventorship, under 35 U.S.C. § 102(g). The district court granted the alleged infringer’s motion for summary judgment on the question of the validity of the patent.

With respect to inventorship, the Federal Circuit determined that in order to demonstrate inventorship, the alleged infringer need only prove either that the inventor conceived of the invention first and was diligent in reducing it to practice or that the inventor reduced its invention to practice before the critical date of the patent-at-issue. Further, in order for an alleged infringer to prove that it reduced the invention to practice before the critical date of the patent-at-issue, it need not prove repeatability, meaning that it need not show that its conception is actually repeatable by those skilled in the art without undue experimentation. Moreover, the prior inventor is not required to establish that it recognized the invention in the same terms as those recited in the patent claim. The Federal Circuit held that the alleged infringer demonstrated reduction to practice by developing a SiC wafer that met all three defect density limitations of all claims of the patent.

With respect to abandonment, suppression, or concealment, the Federal Circuit determined that only process claims require an enabling disclosure in order to provide an adequate disclosure to the public. Because the patent claimed in this case was directed at a product, not a process, the alleged infringer did not have to disclose how it arrived at its results. The Federal Circuit held that the alleged infringer promptly and publicly made its invention, a SiC material with low defect densities, known to the public through a conference presentation and a published paper.

The Federal Circuit upheld the district court’s finding of invalidity as to two claims of the patent, holding that the alleged infringer produced clear and convincing evidence that it had produced the low density SiC crystal prior to the patentee’s date of invention and that the patentee had not produced sufficient evidence to show or raise genuine issues that the alleged infringer abandoned, suppressed, or concealed the invention. The Federal Circuit vacated the district court’s decision that the entire patent was invalid because the patentee had narrowed the scope of its asserted claims before summary judgment, and, therefore, the district court lacked jurisdiction over the unasserted claims.

One judge concurred in part and dissented in part, agreeing that the alleged infringer reduced its invention to practice but disagreeing that the record supported the conclusion that as a matter of law the alleged infringer neither abandoned, suppressed, nor concealed its invention. The dissent argued that simply disclosing the existence of a product is insufficient to make an invention publicly known.

A copy of the opinion can be found here.