Practice Areas

Print PDF

When the doctrine of equivalents results in patent infringement

June 1, 2024
June/July 2024 Cantor Colburn IP Newsletter

As an alternative route to establishing patent infringement liability, the doctrine of equivalents comes with some strict requirements. One patentee’s failure to meet those requirements ended up costing it a hefty jury award on appeal.

A frequency feud

VLSI Technology owns a patent for a system in which at least two devices (for example, computer processors) are coupled to a “bus” that can operate at different frequencies. The invention was intended to improve the performance of portable multimedia devices.

VLSI sued Intel Corporation, alleging several of its microprocessors infringed the patent. The accused microprocessors feature cores and a bus connecting the cores. A controller can change the frequency of the bus or a core on the bus.

A jury didn’t find literal infringement of the patent but awarded VLSI $675 million for infringement under the doctrine of equivalents. Intel appealed to the U.S. Court of Appeals for the Federal Circuit, the appellate court that hears all patent-related appeals.

Insufficient evidence

The doctrine of equivalents provides a limited exception to the legal principle that a patent’s claim meaning defines the scope of rights conveyed by the patent. Essentially, it allows a finding of infringement even though the accused product doesn’t literally infringe a patent claim’s express terms. The infringement is instead based on an “equivalence” between elements of the accused product and the claimed elements of the patent invention. Use of the doctrine, the Federal Circuit has declared, should be “exceptional.”

To limit the doctrine’s use, the patentee must establish, among other things, that the difference between the claimed invention and the accused product was insubstantial. According to the Federal Circuit, the determination of whether a substitute element is only insubstantially different from a claimed element — and therefore an equivalent — considers whether the substitute matches “the function, way, and result of the claimed element.”

In addition, the court has long demanded “specificity and completeness of proof.” The patentee must provide particularized testimony and linking argument on the insubstantiality of the differences between the products.

The Federal Circuit found that VLSI fell short on these two requirements. VLSI’s expert, the court acknowledged, presented his evidence for equivalence using the “function, way, result framework” — but his testimony was insufficient. It included no meaningful explanation of how the accused elements in question worked in substantially the same way as the patented elements.

The expert described the difference between the elements as a “design choice,” or just a matter of where an engineer draws a line on a schematic drawing used to illustrate functions. But, the court said, the focus should be on actual functionality-location differences. And labeling a difference a “design choice” didn’t begin to explain whether the difference in the way the functionalities are actually allocated between devices is an insubstantial one.

Verdict short circuits

The Federal Circuit concluded that VLSI’s evidence didn’t support its doctrine of equivalents theory as a matter of law, meaning that a jury couldn’t possibly come to a contrary conclusion. Therefore, the court reversed the infringement judgment.

© 2024

View Document(s):