The U.S. Court of Appeals for the Federal Circuit affirmed a decision of the Board of Patent Appeals and Interferences (Board) of the U.S. Patent and Trademark Office that a patent applicant failed to show unexpected results where the ranges disclosed in the prior art overlapped the claimed ranges. In re Harris, Case No. 04-1370 (Fed. Cir. May 25, 2005) (Ruder, C.J.).
Harris claimed a nickel-based superalloy comprising nickel and twelve additional elements. The claims were rejected over prior art to Yoshinari, which disclosed a nickel-based alloy comprising the same elements. The concentration ranges of each of the twelve additional elements in the prior art overlapped with Harris’ claimed ranges. In fact, eleven of the ranges disclosed in the prior art completely encompassed Harris’ claimed ranges.
Harris relied on the Federal Circuit decision in In re Peterson to argue that "[the prior art] ranges are too broad to teach any specific alloy to the skilled artisan." Neither the Board nor the Court found the argument persuasive because the prior art in issue here bounded each range recited in Harris’ claims.
Because the Court found the Board properly identified a prima facie case of obviousness (due to the overlapping ranges), the burden shifted to Harris to show unexpected results. To meet its burden, Harris compared one specific alloy to four commercial alloys in an attempt to demonstrate that the claimed alloy had a quantitative improvement in the "stress rupture life." Harris identified one of the commercial alloys to be the "closest prior art" because it differed slightly from the claimed alloy in that the amounts of two elements in the prior art alloy were outside the claimed ranges of these elements. The Court disagreed, noting that the prior art alloy Harris chose for its comparison was no closer than other prior art. The Court held that where each embodiment of the invention was equally representative of the prior art, "a comparison cannot be said to establish" unexpectedly superior results over the prior art.
The Court acknowledged that even though the comparative results showed an improvement in the stress-rupture life, the showing did not represent a "difference in kind" as required to show unexpected results but merely a difference in degree from results obtained by the prior art. Since the prior art teaches that limiting the amount of two elements in the alloy improves "hot corrosion resistance" and "high temperature strength," which are related to stress-rupture life, the evidence supported the Board conclusion that an increase in stress-rupture life was not unexpected.
Finally, the Court agreed with the Board that the showing of unexpected results by Harris was not commensurate in scope with the claimed ranges; Harris relied only on one specific alloy for the showing. According to the Court, "[w]hile Harris’s evidence may show a slight improvement over some alloys, the record does not show that the improved performance would result if the weight-percentages were varied within the claimed ranges."
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