A Blog About Intellectual Property Litigation and the District of Delaware


Entries for tag: doe

Coffee Equals
Charles "Duck" Unitas, Unsplash

Most patent litigators know that the reverse doctrine of equivalents exists, and provides a way to argue non-infringement even if an accused product meets the literal terms of a claim. But it tends to be one of those issues that floats around in the ether, waiting for the right case, and it is rarely applied in practice.

Judge Connolly had an occasion last week to address the issue, resolving a motion for summary judgment of no reverse DOE, and took the opportunity to dig into some of the history of the reverse doctrine of equivalents. He first quoted the Federal Circuit's description of what the doctrine is:

the reverse doctrine of equivalents . . …

Yesterday, visiting Judge Bataillon excluded a patentee's expert opinion where the expert tried to use the doctrine of equivalents to skirt the Court's construction of a term.

The Court had initially rejected a preliminary injunction motion by the patentee, holding that it had failed to show a likelihood of success on infringement based on its proposed claim construction.

The patentee then proposed the same construction during claim construction before the magistrate judge, who issued an R&R rejecting it.

The patentee then objected to the R&R, but the Court adopted the construction in the R&R and again rejected the patentee's proposed construction.

Specifically, the Court held that the claims required two elements that each have a different thickness and composition: …

Although the Pennypack factors for exclusion are notoriously difficult to meet, judges in D. Del. have been excluding late-disclosed theories more frequently than in the past.

Case in point: on Friday, Judge Andrews granted a motion to strike DOE theories asserted for the first time in an opening expert report. The plaintiff offered a number of excuses for disclosing the theories when it did—"it was only able to collect evidence to support its new DOE theories" after a COVID-delayed source code review, it lacked supporting evidence until a technical deposition in November 2020, and so on.

Judge Andrews not only rejected these excuses, but took it a step further—coming very close to finding that the plaintiff acted in …

Chief Judge Stark this week granted a motion of non-infringement under the doctrine of equivalents due to the slim DOE analysis relied on by the patentee's expert.

Interestingly, the expert had offered some testimony framed in terms of the usual function-way-result DOE test:

[T]he Accused Products perform substantially the same function (producing densitometry/densitometric models for use in assessing bone density), in substantially the same way (determining linear attenuation coefficients of an object in several tomographic scans and combining this information using the Feldkamp algorithm to determine the grayscale values of voxels and the corresponding HU units thereof of a 3D CBCT volume of the object), to achieve substantially the same result (3D volumes that include information for depicting quantitative differences …