Maquet Cardiovascular LLC v. Abiomed, Inc. et al. (D. Mass. 17-cv-12311).

Maquet accused Abiomed of infringing U.S. Patent No. 10,238,783, covering intravascular blood pumps.  Maquet moved to strike portions of Abiomed’s expert report and rebuttal report, contending that these raised new invalidity and noninfringement theories not disclosed in Abiomed’s contentions.  A claim construction order issued in September 2022, which was modified upon appeal in March 2025.  Shortly thereafter, the parties filed their final invalidity and infringement contentions, and neither party subsequently moved to amend these final contentions.

Judge Saylor looked to the Local Patent Rules for the District of Massachusetts (L.R. 16.6), which mandates disclosure of infringement, noninfringement, and invalidity contentions early in a case.  These disclosures can only be amended or supplemented upon leave of court upon a timely showing of good cause, and the rule provides for exclusion of evidence where such does not occur.

Maquet first sought to strike expert testimony relating to failure to meet the written description requirement.  Judge Saylor noted that the L.R. 16.6 requires disclosure of invalidity theories based on written description, and that the scheduling order in the case had a similar requirement.  He noted that, while Abiomed had disclosed invalidity based on failure to meet the written description requirement, its final invalidity contentions disclosed only one ground – that the asserted patent only disclosed cable-driven pumps.  The contentions did not disclose that the patent only described pumps connected to a cannula, which the expert report addressed.  He noted that L.R. 16.6. requires more than just the general grounds for an invalidity contention – it requires disclosure of evidence sufficient to support an invalidity defense.  Here, the final contentions failed to provide sufficient evidence for the particular written description argument, and Judge Saylor accordingly struck this contention.

Judge Saylor denied the motion with respect to the expert’s reference to a different Abiomed patent, the “’100 Patent,” that was used to provide support for the expert’s position that only the cable-driven blood pump is supported.  The ‘100 Patent is a family member to the patents-in-suit, and is involved in a different, related patent lawsuit between the parties.  While Abiomed’s final invalidity contentions do not cite this reference, Judge Saylor determined that the Local Rules do not require the provision of “all” evidence to support an invalidity theory, but only “sufficient” evidence to support the invalidity theories advanced.  He further noted that Maquet had been litigating the ‘100 Patent since 2016, meaning that Maquet could not have been surprised by its relevance.  Accordingly, he declined to strike this portion of the expert report.

Judge Saylor struck opinions of obviousness over three particular references.  While Abiomed did disclose obviousness theories in general, and had identified all of the references in its invalidity contentions, it had not identified the combination of the three particular references in combination together.  This was contrary to the Local Rules’ requirement that the accused infringer identify “each” combination and further specify “specifically” where in the combined references each element of the asserted claims could be found.  Judge Saylor determined that a listing of prior art that “might be combined” was insufficient, particularly when the potential combinations numbered in the thousands, as was the case here.

Judge Saylor also declined to strike single-reference obviousness opinions, finding that the Local Rule requirement for single-reference obviousness disclosures was less stringent than for multi-reference obviousness theories.  While Abiomed’s invalidity contentions did not specifically suggest particular modifications to the references in light of the knowledge of a person of ordinary skill in the art, Judge Saylor found that this was not required by the Local Rules.

Judge Saylor also agreed that Abiomed’s expert had proffered noninfringement theories that were not contained in Abiomed’s final contentions, as required by the Local Rules.  While Abiomed did disclose theories related to the particular claim limitation, its contentions did not address the specific component of its product that was alleged to differential the product from the limitation.  He further struck a noninfringement position in the expert report that had been disclosed in an intervening set of contentions, but that had been removed from the final set of contentions (although the final set had incorporated all previous contentions “be reference”).  Judge Saylor determined that allowing a removed contention to be reincorporated would run counter to the goal of the rules to narrow issues over the course of a litigation, and struck this portion of the expert’s rebuttal report.

Abiomed further sought to add an affirmative defense of ensnarement following the close of fact discovery.  Ensnarement is a doctrine that precludes the use of the doctrine of equivalents where the scope of equivalents sought would be covered by, or “ensnare,” the prior art.  Judge Saylor noted that ensnarement, unlike other affirmative defenses, need not actually be pled, but that Federal Circuit precedent held that the defense could be waived where it was presented in an untimely fashion and the delay resulted in prejudice to the opposing party.  The Lo0cal Rules do not specify the timing for disclosure of such a defense, and therefore would not preclude Abiomed from raising it at this point in the litigation.  As Abiomed first raised the defense prior to the presentation of expert reports, and as “ample time” remained before trial, Judge Saylor declined to deem the defense waived and refused to strike portions of Abiomed’s expert report concerning ensnarement.  He did determine that Abiomed bore the initial burden of identifying allegedly ensnared prior art, before Maquet would be required to propose a hypothetical claim that covered the Accused Products.