In Dionex Softron GMBH vs. Agilent Technologies, Inc., the Court of Appeals for the Federal Circuit (“Federal Circuit”) affirmed the Patent Trial and Appeal Board’s (“Board”) decision in an interference proceeding to award priority to Agilent Technologies, Inc. (“Agilent”) over Dionex Softron GmbH (“Dionex”).  In particular, the Federal Circuit affirmed the Board’s application of the “rule of reason” for determining whether there was sufficient corroborating evidence to support an inventor’s testimony regarding the pertinent date of invention.


An interference proceeding is a contest conducted by the Board to determine which party has priority as the first to invent under pre-AIA 35 U.S.C. 135(a).  An inference proceeding exists if the subject matter of a claim of an application is anticipated or rendered obvious in view of the subject matter of a claim of an opposing party’s patent or application. When an interference is declared, there is a description of the interfering subject matter, called a “count’.” Every count must have at least one corresponding claim for each party.

 In order to demonstrate priority as the first inventor to invent, a party must demonstrate both conception and reduction to practice of the claimed invention before the other party. Additionally, “an inventor’s testimony must be corroborated by independent evidence.” Cooper v. Goldfarb, 154 F.3d 1321, 1327 (Fed. Cir. 1998). “However, a ‘rule of reason’ analysis is applied to determine whether an inventor’s testimony regarding reduction to practice has been sufficiently corroborated.” Id. “Sufficient corroboration” does not require “corroboration for every factual evidence contested by the parties” but whether “the evidence as a whole is persuasive.” Id.

An interference proceeding was launched between Agilent and Dionex when Dionex copied Agilent’s amended claims. In the proceeding, Agilent and Dionex separately moved for judgment on the basis of priority due to their respective alleged dates of conception and reduction to practice.  As the later filing party (junior party), Agilent was required to prove priority by a preponderance of the evidence. The Board granted Agilent’s motion and denied Dionex’s motion, finding that Agilent proved conception as of May 1, 2007 and actual reduction to practice as of June 1, 2007- well before Dionex’s earliest alleged conception date of December 4, 2007.


On appeal Dionex argued that there was a lack of sufficient evidence to support the Board’s finding of corroboration. Specifically, Dionex argued the corroborating testimony of one of Aglient’s witnesses (“Bäuerle”) was not independent because Bäuerle lacked knowledge regarding features of the invention, such as his failure to demonstrate knowledge of the prototype’s hydraulic configuration and the purpose of “grooves” within the prototype. The Federal Circuit rejected Dionex’s arguments by arguing that Bäuerle was not required to know every detail under the rule of reason.

 Further, the Federal Circuit rejected Dionex’s argument that a document failed to corroborate the co-inventor’s testimony when the document was modified after the purported date of reduction to practice because substantial evidence, including Bäuerle’s testimony, corroborated that the document depicted a prototype meeting the requirements of the claim at the pertinent date.

Lastly, the Federal Circuit rejected Dionex’s argument that a negative interference must be drawn against Agilent due to the failure of one of the co-inventors to testify or lack of corroborating documents that Dionex argued were required to be produced under industry norms.  In particular, the Federal Circuit found that the Board did not abuse its discretion in deciding to not draw a negative inference for the failure to call the co-inventor as a witness when Agilent represented that the testimony would have been cumulative of the other co-inventor’s testimony. Additionally, the Federal Circuit found that the Board was well within its discretion to reject Dionex’s assertion that “industry norms” would have caused Agilent to create documents other than those produced in the interference.

Thus, under the Federal Circuit’s flexible application of the “rule of reason”, the Board has broad discretion to determine whether independent evidence is sufficient to support a priority date during interference proceedings.