First and foremost, the AIA statutory amendment that removed best mode from the list of invalidating conditions for issued patents was not given retroactive effect for cases that were filed before the new statute was enacted. Second, the question of whether the best mode requirement has been satisfied is highly factual. Even if the inventor cannot provide any other specific embodiment that would be preferable to the one he deliberately left out of the application, this may not be sufficient to satisfy the subjective requirement that he regarded the excluded embodiment as the best mode.
Background / Facts: The patents at issue in this case are directed to photolithography systems used to make electronic products such as liquid crystal display panels. The claimed systems selectively expose a substrate to electromagnetic radiation through a mask by the use of partially overlapping scans of the mask and substrate to ensure that the substrate is exposed uniformly and seamlessly. In each patent, the asserted claims recite, as part of the claimed lithography system, an “illumination subsystem” satisfying certain requirements. In a separate patent application filed before the applications for the patents in suit, the inventor described and claimed a particular illumination system not mentioned in the patents in suit. Both at his deposition and in his declaration, the inventor failed to identify any illumination system he deemed suitable for use in practicing the asserted claims other than the one described in the prior patent.
Issue(s): Whether this evidence is sufficient to show that the inventor believed the illumination system of the prior patent was the best mode for practicing the inventions of the asserted claims and concealed that best mode from the public.
Holding(s): No (at least not on summary judgment). In order to determine whether there has been a violation of the best mode requirement, two factual questions must be answered. The first is whether, at the time of filing the patent application, the inventor had a best mode of practicing the claimed invention – a subjective question. The second is whether, assuming the inventor had a preference for one mode over all others, the inventor objectively concealed his preferred mode from the public. This case focuses mainly on the first question. The defendants did not obtain a direct admission from the inventor either that he knew of a best mode for practicing the asserted claims or that he concealed it. What they elicited was a repeated denial on the inventor’s part that the illumination system of the prior patent was the best mode for practicing the limitation of the asserted claims, accompanied by an inability of the inventor to identify any other. While curious and perhaps incredible, this evidence is not conclusive (e.g., it is possible that the inventor really could not recall, which is a question of credibility for the jury).