## Facts

- U.S. Patent No. 4,323,071 covered a balloon angioplasty catheter used to treat arterial stenosis and listed Drs. John B. Simpson and Edward W. Robert as inventors.
- In the late 1970s, Simpson and Robert attempted to develop an angioplasty catheter and experimented with multiple balloon materials, including polyvinylchloride and Teflon, with unsatisfactory results.
- Simpson and Robert were referred to Robert L. Hess, an engineer at Raychem Corporation with experience in heat-shrinkable materials.
- Hess provided samples of Raychem tubing and technical suggestions about possible balloon construction using those materials.
- Advanced Cardiovascular Systems, Inc. (ACS) became the patent assignee.
- Hess later claimed that his provision of tubing and related suggestions made him a co-inventor and sought correction of inventorship and related relief.
- The Northern District of California rejected Hess’s inventorship claim, finding his contributions did not amount to conception of the claimed invention and also made rulings excluding certain expert testimony offered by Hess.

## Issues

1. Whether Hess’s provision of materials and suggestions constituted a contribution to the conception of the claimed invention sufficient for joint inventorship.
2. Whether the district court committed reversible error in evidentiary rulings, including exclusion of certain expert testimony offered to support Hess’s inventorship claim.

## Decision

- The Federal Circuit affirmed the district court’s judgment.
- The court held Hess was not a co-inventor because the record supported that he provided materials and general suggestions but did not contribute to conception of the claimed subject matter.
- The court upheld the district court’s evidentiary rulings, finding no abuse of discretion and no prejudice warranting reversal.

## Legal Principles

- Joint inventorship requires a contribution to the conception of the invention as claimed; contributions need not be equal but must relate to the claimed subject matter.
- Conception is the formation in the inventor’s mind of a definite and permanent idea of the complete and operative invention.
- A person is not a co-inventor by merely explaining concepts well known in the art, supplying materials, or explaining how to use supplied materials, without contributing to the claimed inventive concept.
- Inventorship challenges require corroborated evidence; inventorship is a question of law based on underlying factual findings reviewed for clear error.
- Evidentiary rulings, including exclusion of expert testimony, are reviewed for abuse of discretion, and reversal requires a showing of prejudice.

## Conclusion

The Federal Circuit affirmed that Hess’s assistance in supplying tubing and offering general technical suggestions did not establish joint inventorship because he did not contribute to the conception of the invention reflected in the patent claims, and the challenged evidentiary rulings did not warrant reversal.


Hess v. Advanced Cardiovascular Sys., Inc., 106 F.3d 976 (Fed. Cir. 1997)