Fluidigm Corporation v. Ionpath

Background

Fluidigm Corporation, the patent owner, sued Ionpath, Inc. Fluidigm served infringement contentions for U.S. Patent Nos. 10,180,386 and 10,436,698. Ionpath later served invalidity contentions. After the parties exchanged formal proposed interpretations of patent terms on May 6, Fluidigm did not move to amend its infringement contentions within 28 days.

On July 27, Fluidigm served an expert report from Dr. Gary Hieftje. Ionpath argued that the report raised infringement theories that Fluidigm had not disclosed: theories treating certain claim limitations as “means-plus-function” limitations under 35 U.S.C. § 112(6), and theories under the doctrine of equivalents, which can treat a product feature as infringing even when it does not literally meet a claim limitation. Ionpath also argued that Dr. Hieftje improperly offered opinions about claim construction—the legal interpretation of patent claims—even though Fluidigm had not identified him as a claim-construction expert.

Ionpath moved to strike the challenged material. Fluidigm initially opposed the requested amendment but later withdrew its opposition. The parties were preparing for an expedited patent proceeding involving expert discovery, summary-judgment briefing, and a hearing.

Disclosure and amendment rule

The court held that the Northern District of California’s patent local rules require operative infringement and invalidity contentions to include backup theories that a party may assert if the opposing party’s proposed claim construction is adopted. The duty begins when the parties exchange their formal Rule 4-2 claim-construction disclosures. A party must move to amend its contentions promptly, with 28 days generally being the outside limit.

The court stated that this duty applies when the opposing party offers one clear construction, not when it offers multiple alternative constructions. The duty also does not arise merely from a letter or email. If the opposing party later changes its construction in a joint statement or opening brief, that change may provide a new opportunity to seek amendment.

Fluidigm’s infringement theories

The court found that Fluidigm’s operative infringement contentions did not disclose the means-plus-function or doctrine-of-equivalents theories presented in Dr. Hieftje’s report. The court rejected Fluidigm’s argument that these theories did not need to be disclosed because they were only backup theories responsive to Ionpath’s proposed constructions.

Fluidigm should have moved to amend by June 3, 28 days after the May 6 disclosures, but did not do so. Ionpath first encountered the new theories on July 27, when it served its own expert invalidity report. The court found that Ionpath had been genuinely prejudiced because timely disclosure would have given it more time to investigate the theories, conduct discovery, prepare responses, and develop invalidity arguments.

Despite Fluidigm’s lack of diligence, the court exercised its discretion to allow the amendment. The court noted that the expedited patent proceeding had to be delayed for other legitimate reasons and that extending the delay further would give Ionpath the time it otherwise would have had to respond. Fluidigm was therefore permitted to amend its infringement contentions to include the challenged means-plus-function and doctrine-of-equivalents theories. The court limited any further amendment absent exceptionally strong justification and a diligent motion.

Expert’s claim-construction opinions

Fluidigm had identified four other experts in its Rule 4-2 disclosures but had not identified Dr. Hieftje as a claim-construction expert. The court determined that portions of his infringement report went beyond infringement analysis and offered opinions about the correct interpretations of disputed claim terms, including criticisms of Ionpath’s proposed interpretations.

The court ordered Fluidigm to amend the infringement report to remove Dr. Hieftje’s opinions about claim construction and his judgments about Ionpath’s claim constructions.

Disposition

The court allowed Fluidigm to amend its infringement contentions to add the specified means-plus-function and doctrine-of-equivalents theories. It ordered Fluidigm to remove the improper claim-construction opinions from Dr. Hieftje’s report. It continued the patent proceeding and set new deadlines for amended reports, briefing, and a telephonic hearing.

The court granted Ionpath’s administrative motion to seal sensitive personal information. Except to the extent addressed by the amendment and report-revision rulings, the court denied Ionpath’s motion to strike. The order did not decide the parties’ ultimate infringement, invalidity, or claim-construction disputes.