## Facts

- SciMed owned three patents directed to balloon dilatation catheters used in coronary angioplasty.
- The patents described catheters with multiple shaft sections and a two-lumen structure: a guide-wire lumen and an inflation lumen.
- The common specification repeatedly described the lumens as arranged coaxially, with the guide-wire lumen inside an annular inflation lumen.
- The specification contrasted coaxial lumens with prior-art “dual lumen” (side-by-side) designs and described dual-lumen structures as inferior and outside the invention.
- ACS made accused catheters that used a dual-lumen configuration rather than coaxial lumens.
- SciMed sued ACS for literal infringement and infringement under the doctrine of equivalents.
- The district court construed the asserted claims as limited to coaxial-lumen catheters and granted summary judgment of non-infringement; SciMed appealed.

## Issues

1. Whether the patents’ specification limited the asserted claims to catheters with coaxial lumens, excluding dual-lumen configurations from the literal claim scope.
2. Whether, despite that limitation, ACS’s dual-lumen catheters could infringe under the doctrine of equivalents.

## Decision

- The Federal Circuit affirmed summary judgment of non-infringement.
- The court held the asserted claims were limited to coaxial lumens because the specification defined the invention in those terms and disclaimed dual-lumen designs.
- The court further held SciMed could not use the doctrine of equivalents to cover dual-lumen structures that the specification treated as outside the invention.

## Legal Principles

- Claim scope may be narrowed where the specification repeatedly and consistently characterizes a particular structure as “the invention” and makes clear that alternatives are excluded.
- Language describing “the present invention” and “all embodiments” as having a specific feature can constitute a disclaimer, not merely a description of preferred embodiments.
- A specification-based disclaimer that narrows literal claim scope also limits the doctrine of equivalents; a patentee cannot recapture subject matter the patent describes as outside the invention.

## Conclusion

The Federal Circuit held that clear, consistent definitional statements in the specification limited SciMed’s catheter claims to coaxial-lumen structures and barred both literal and equivalents theories against ACS’s dual-lumen catheters, making summary judgment of non-infringement proper.


SciMed Life Sys., Inc. v. Advanced Cardiovascular Sys., Inc., 242 F.3d 1337 (Fed. Cir. 2001)