The Federal Circuit recently loosened the rules regarding obviousness in In re: Blaise Laurent Mouttet, No. 2011-1451 (Fed. Cir. June 26, 2012). In affirming a Patent Office rejection of inventor Blaise Laurent Mouttet’s crossbar arithmetic processor invention, the Court held that prior art references do not necessarily teach away from a proposed design merely because they suggest the use of a preferred embodiment over a disclosed, but non-selected, alternative.

Mouttet submitted patent application No. 11/395,232, entitled “Crossbar Arithmetic Processor,” on April 3, 2006. It discloses a programmable arithmetic unit capable of performing addition, subtraction, and division using nanoscale materials in a “crossbar array”—a grid of microscopic conductive wires in which the wire junctions are bridged using a thin film or molecular component. By controlling the voltages applied to individual wires, each junction can be programmed to be in a high or low resistance state, allowing the grid to store data in binary form that a post-processing unit can output as numerical values.

The U.S. Patent Office rejected Mouttet’s claims as unpatentable over a prior publication and four prior art patents, including U.S Patent No. 5,249,144 issued to Falk. The Falk ’144 patent disclosed a device for performing arithmetic and logic operations. In the Patent Office’s estimation, Falk disclosed all of the elements of Mouttet’s invention, except that Falk’s crossbar array used intersecting optical channels instead of electronic circuitry. In Falk, the intensity of light at each intersection along the crossbar’s optical paths represented particular logic states used to perform the arithmetic processes. Because Mouttet’s claims required use of wires in the array, the Patent Office combined the teachings of Falk with those of an article by Das, which taught a nanoscale crossbar array of electrical wires with molecular switches.

On appeal, Mouttet argued that Falk taught away from Mouttet’s claimed invention, relying on a passage in Falk stating that optical devices are preferred to electronic devices because optical devices possess “interconnect possibilities that do not exist with electronic hardware.” Under U.S. patent law, “teaching away” from the claimed invention can preclude a finding that the reference renders the claimed invention obvious. As the Supreme Court explained in KSR International Co. v. Teleflex, Inc., 550 U.S. 398, 416 (2007), “when the prior art teaches away from combining certain known elements, discovery of a successful means of combining them is more likely to be nonobvious.” On March 29, 2011, the Patent Office’s Board of Patent Appeals and Interferences rejected Mouttet’s argument and affirmed the examiner’s rejection, agreeing that an electrical engineer with several years of experience would have recognized that combining the teachings of the prior art references would yield Mouttet’s claimed circuit.

On appeal, the Federal Circuit affirmed the finding that Mouttet’s invention was obvious in light of Falk and the other prior art. The court stated that the mere disclosure of alternative designs in a prior art reference does not teach away from a non-preferred alternative. Falk noted certain advantages to using optical devices in his design, but did not go as far as to suggest that using wires instead of optical channels would destroy the operability of the circuit as a programmable arithmetic unit. The Court further explained that “just because better alternatives exist in the prior art does not mean that an inferior combination is inapt for obviousness purposes.” In particular, the Court held that even if Falk suggested that electrical circuits are inferior to optical circuits for some purposes, Mouttet failed to cite any reference showing that Falk’s claimed invention would be unlikely to work using electrical circuitry.

Following this decision, it may be more difficult for applicants (or litigants) to show that a prior art reference disclosing multiple alternatives teaches away from the claimed invention, even in those instances where the reference expressly states that some alternatives are inferior to the preferred embodiment. When trying to oppose an obviousness rejection on the basis that a reference “teaches away” from the claimed invention, it will be important for applicants to establish that the reference does more than merely state a preference for a non-anticipating embodiment over a potentially anticipating, alternative. Applicants should emphasize that the reference affirmatively discourages using the non-preferred embodiment, or that the reference teaches that the non-preferred embodiment would be unlikely to work.