## Facts

- Competing inventors pursued patent claims to artificial vascular grafts made from expanded polytetrafluoroethylene (PTFE), where graft performance depended on controlling fibril length (inter-nodal distance) in the PTFE microstructure.
- A PTO interference proceeding (Interference No. 101,100) was declared to determine priority of invention.
- The Board found Cooper had earlier conception, but held Goldfarb was first to achieve actual reduction to practice based on successful graft experiments within the count and corroborated measurements and testimony.
- The Board further concluded Cooper had not properly raised the issue of inurement and therefore did not decide whether Goldfarb’s work could be credited to Cooper.
- Cooper appealed under 35 U.S.C. § 141, challenging the Board’s reduction-to-practice determination and the Board’s refusal to consider inurement.

## Issues

1. Whether substantial evidence supported the Board’s finding that Goldfarb was the first to actually reduce the interference count to practice.
2. Whether the Board erred in refusing to consider inurement on the ground that Cooper had not properly raised it.

## Decision

- The Federal Circuit affirmed the Board’s determination that Goldfarb achieved actual reduction to practice before Cooper.
- The Federal Circuit reversed the Board’s determination that Cooper failed to raise inurement.
- The case was remanded for the Board to decide whether Goldfarb’s reduction-to-practice activities inured to Cooper’s benefit.

## Legal Principles

- Actual reduction to practice in an interference requires (1) construction of an embodiment within the scope of the count and (2) proof, supported by corroborated evidence, that it worked for its intended purpose.
- Priority may rest on earlier actual reduction to practice even if the opposing party conceived first, unless the first conceiver proves facts (such as diligence or other doctrines) that legally preserve priority.
- Inurement permits crediting another person’s reduction-to-practice acts to the inventor who previously conceived, if the actor performed the work on the inventor’s behalf and not in opposition to the inventor.
- A party raises inurement without “magic words” when the substance of its arguments and evidence fairly presents the issue; when fairly presented, the tribunal must address it.

## Conclusion

The Federal Circuit left intact the finding that Goldfarb was first to actually reduce the claimed PTFE vascular graft to practice, but required the Board to consider on remand whether that reduction to practice should be legally attributed to Cooper under the doctrine of inurement.


Cooper v. Goldfarb, 154 F.3d 1321 (Fed. Cir. 1998)