## Facts

- GuideTech owned three related patents covering circuitry used in time interval analyzers to detect timing errors in high-speed digital systems.
- The named inventor later left GuideTech and formed Brilliant, whose BI-series analyzers (including BI200 and BI220) GuideTech accused of infringing.
- Brilliant filed a declaratory-judgment action seeking findings of noninfringement of U.S. Patent Nos. 6,226,231 (’231), 6,091,671 (’671), and 6,181,649 (’649).
- For the ’671 and ’649 patents, the district court construed “operatively disposed in parallel” to mean “arranged in a manner capable of forming alternative paths of current such that current can flow across one path or the other path”; the construction was not disputed on appeal.
- GuideTech’s expert acknowledged the accused capacitor was located within the “first current circuit,” not on an alternative branch, but opined the accused circuit operated equivalently to the claimed arrangement.
- For the ’231 patent, GuideTech relied on schematics and expert testimony to show the accused products contained multiple measurement circuits within a signal channel in a parallel configuration.
- The district court granted summary judgment of noninfringement: no literal infringement of all three patents and no infringement under the doctrine of equivalents (DOE) for the ’671 and ’649 patents, reasoning that equivalence would “vitiate” the “in parallel” limitation.

## Issues

1. Whether summary judgment of no literal infringement of the ’231 patent was proper as to the limitation requiring “a plurality of measurement circuits defined within said signal channel in parallel with each other.”
2. Whether summary judgment of no infringement under the doctrine of equivalents for the ’671 and ’649 patents was proper where the accused capacitor was not literally “operatively disposed in parallel” with the first current circuit.
3. Whether the district court correctly applied “vitiation” to reject GuideTech’s DOE theory as a matter of law.

## Decision

- Reversed summary judgment of no literal infringement of the ’231 patent because the record contained genuine disputes of material fact regarding whether the accused analyzers included multiple measurement circuits in parallel within the signal channel.
- Affirmed summary judgment of no literal infringement of the ’671 and ’649 patents because the accused capacitor was undisputedly in-line within the first current circuit and thus did not meet the “operatively disposed in parallel” limitation under the agreed construction.
- Reversed summary judgment of no infringement under the doctrine of equivalents for the ’671 and ’649 patents because GuideTech’s expert evidence could allow a reasonable jury to find equivalence under the function–way–result framework.
- Remanded for further proceedings.

## Legal Principles

- Summary judgment on infringement is improper when competing reasonable inferences can be drawn from technical evidence and expert testimony on whether claim limitations are met.
- Literal infringement fails where an undisputed structural fact places the accused element outside the scope of a claim limitation as construed.
- “Vitiation” is not a categorical exception to the doctrine of equivalents; it reflects the legal conclusion that, on the evidence, no reasonable jury could find equivalence for a particular limitation.
- A party can defeat summary judgment on DOE by presenting evidence (including expert analysis) that the accused element performs substantially the same function, in substantially the same way, to achieve substantially the same result as the claimed element, unless the difference is substantial as a matter of law.

## Conclusion

The Federal Circuit held that factual disputes precluded summary judgment on literal infringement of the ’231 patent and on equivalents for the ’671 and ’649 patents, and clarified that “vitiation” cannot replace record-based analysis of whether a reasonable jury could find equivalence.


Brilliant Instruments, Inc. v. GuideTech, LLC, 707 F.3d 1342 (Fed. Cir. 2013)