## Facts

- Competing inventors claimed priority to an assay/method for identifying compounds that inhibit farnesyl transferase (FT) to reduce ras-mediated cell growth.
- The dispute arose in a USPTO patent interference between Barbacid’s issued patent and Brown’s pending application.
- Brown was the senior party based on an earlier effective filing date (April 18, 1990), though the application was filed later.
- Barbacid’s team was found by the Board to have actually reduced the invention to practice no later than March 1990.
- Brown asserted an earlier conception date of September 1989, relying mainly on inventor Reiss’s laboratory notebooks and his testimony explaining the entries; another scientist (Casey) offered supporting testimony about late-1989 discussions.
- The Board rejected Brown’s conception case for lack of adequate corroboration, treated diligence as moot, and awarded priority to Barbacid.
- Brown appealed the Board’s priority determination to the Federal Circuit.

## Issues

1. Whether the Board applied an improper corroboration standard by discounting laboratory notebooks and related testimony offered to prove Brown’s alleged September 1989 conception.
2. Whether the Board erred by failing to evaluate Brown’s evidence of reasonable diligence from just before Barbacid’s March 1990 reduction to practice through Brown’s April 1990 effective filing date.

## Decision

- The Federal Circuit vacated the Board’s award of priority to Barbacid and remanded.
- The court held the Board misapplied corroboration law by effectively demanding undue independent authentication and failing to assess the totality of corroborative evidence.
- The court held the Board also erred by not considering diligence once conception evidence is assessed under the correct standard.
- On remand, the Board was instructed to reassess conception under a proper rule-of-reason analysis and, if conception is established, to decide diligence during the critical period.

## Legal Principles

- In an interference, a party asserting earlier conception must prove a definite and permanent idea of the complete and operative invention.
- An inventor’s testimony on conception must be corroborated by independent evidence, evaluated under a flexible “rule of reason” considering all pertinent evidence in combination.
- Contemporaneous documentary evidence, including laboratory notebooks, is classic corroboration and must be weighed with explanatory testimony rather than disregarded through rigid authentication demands.
- If earlier conception is shown, the party must also prove reasonable diligence from just before the opponent’s reduction to practice through the party’s own reduction to practice or filing date.
- The Federal Circuit reviews the Board’s legal conclusions de novo and its factual findings for substantial evidence.

## Conclusion

The Federal Circuit set aside the interference priority award because the Board applied an overly rigid corroboration approach that discounted laboratory notebooks and failed to reach diligence; it remanded for a full reevaluation of conception and, if established, diligence under the rule-of-reason standard.


Brown v. Barbacid, 276 F.3d 1327 (Fed. Cir. 2002)