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  • Hess v. Advanced Cardiovascular Systems, Inc.Hess v. Advanced Cardiovascular Systems, Inc.
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Hess v. Advanced Cardiovascular Systems, Inc.

United States Court of Appeals for the Federal Circuit
106 F.3d 976 (1997)


Drs. John Simpson and Edward Roberts were the named inventors on a patent disclosing a balloon angioplasty catheter. During initial stages of development, Simpson and Roberts experimented with various materials, each turning out to be ineffective. Simpson and Roberts contacted Hess (plaintiff), an engineer at RayChem Corporation. Simpson and Roberts explained their inability to find a suitable material for constructing the catheter balloon. Hess had no prior experience with angioplasty, but he suggested that Simpson and Roberts use a heat-shrinkable material manufactured by RayChem. Hess demonstrated how the tubing material could be used to form a balloon by applying heat, which was a process generally known to other companies at the time. Hess also provided Simpson and Roberts with samples of the material, which the doctors used in their development of the catheter. After extensive experimentation, Simpson and Roberts successfully constructed the angioplasty balloon using a method called free-blowing, which Hess did not suggest. After applying for a patent for the catheter, Simpson and Roberts founded Advanced Cardiovascular Systems, Inc. (ACS) (defendant), to which they assigned the patent. Hess sued ACS, seeking correction of the patent to include Hess’s name as a co-inventor. The district court found in ACS’s favor, concluding that Hess did not establish co-inventorship because Hess’s involvement did not rise to the level of conceiving the invention. Hess appealed.

Rule of Law


Holding and Reasoning (Friedman, J.)

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