Back in July and December 2020, we wrote about the seeming rise in allegations of infringement allegations under the doctrine of equivalents (DOE) in life sciences cases. We noted that in those recent cases the Federal Circuit provided in-depth analyses of the application of DOE, prosecution history estoppel, and the various other limits on the DOE, and suggested that potential infringers needed to keep an eye on the substantive evolution of the doctrine.

But a recent decision in Arendi S.A.R.L. v. Motorola Mobility LLC, Civ. Action No. 1-12-cv-01601 (D. Del.) (docket entry 250), reminds practitioners that before addressing the substantive elements of DOE, they should make sure it’s properly in the case at all. In that case, Arendi’s original complaint accused Motorola of infringing “literally or under the doctrine of equivalents.” Its initial disclosures, filed under the Default Standard for Discovery, accused Motorola of “infringing,” but did not mention the DOE. Similarly, Arendi’s claim charts referred to “infringement” without distinguishing between literal infringement and the DOE. After the close of fact discovery, Arendi submitted its infringement expert reports, noting that “[t]o the extent that the foregoing evidence does not demonstrate literal infringement of this element, the evidence demonstrates infringement . . . under the doctrine of equivalents.” Its reply infringement expert reports, Arendi included substantive opinions relating to the DOE.

Motorola moved to strike portions of those reports discussing the DOE, which the Court granted:

Arendi’s passing reference to DOE in its complaints followed by its lack of affirmative disclaimer of DOE theories . . . does not come close to satisfying Arendi’s obligation to articulate, in a timely manner, contentions and then expert opinion and linking evidence specifically directed to the claim elements it contends are met (at least contingently) by a theory of equivalents, under the function/way/result and/or insubstantial differences tests.

Thus, because Motorola “had no opportunity to pursue fact or even expert discovery to counter the new DOE theories, which they might have done by pursuing, for example, different theories of non-infringement, such as ensnarement,” the Court struck the DOE theories.

Articulating DOE theories for the first time in expert reports is not uncommon. Some courts have local patent rules that would bar, absent a showing of good cause, such late introduction of DOE theories, including the Northern District of California, District of New Jersey, and Eastern District of Texas. For example, the Patent Local Rules for the Northern District of California demand disclosure of “[w]hether each limitation of each asserted claim is alleged to be literally present or present under the doctrine of equivalents.” In contrast, Delaware’s Default Standard for Discovery merely requires disclosure of an “initial claim chart,” and many common patent litigation courts do not have any such requirements.

The recent decision in the Arendi case suggests that defendants in all forums should pay close attention to the availability to strike evidence relating to the doctrine of equivalents, and plaintiffs should be careful to not simply rely on boilerplate language in the complaint.