## Facts

- Competing patent applications claimed substantially the same laser apparatus (light amplification by stimulated emission of radiation), leading the Patent Office to declare an interference.
- Schawlow and Townes were the senior party based on an earlier filing date of July 30, 1958.
- Gould was the junior party based on a later filing date of April 6, 1959.
- Neither side relied on an earlier actual reduction to practice; the parties treated their respective filing dates as constructive reduction to practice.
- Gould relied on earlier conception evidence (including notebooks) indicating he had conceived the invention before the senior party’s filing date.
- To prevail as the junior party, Gould sought to prove prior conception and reasonable diligence from just before the senior party’s filing date through Gould’s filing date.
- The Board of Patent Interferences found Gould’s evidence insufficient to establish continuous, corroborated diligence during the critical period and awarded priority to Schawlow and Townes.
- Gould appealed to the United States Court of Customs and Patent Appeals.

## Issues

1. Whether a junior party who conceived first but filed second must account for the entire critical period and prove reasonable diligence throughout that period to establish priority under 35 U.S.C. § 102(g).
2. Whether Gould’s evidence was sufficiently specific and corroborated to show reasonable diligence during the critical period.

## Decision

- The court affirmed the Board’s award of priority to Schawlow and Townes.
- The court held that a party chargeable with diligence must account for the entire period during which diligence is required and prove reasonable diligence during that time.
- The court concluded that Gould failed to provide sufficiently specific, corroborated evidence showing continuous activity directed to reduction to practice across the critical period.
- The court rejected Gould’s contention that the Board applied an impermissibly “formalistic” standard, reiterating that the governing test is reasonable (not perfect) diligence.

## Legal Principles

- In an interference, a junior party who seeks priority based on earlier conception must prove (1) prior conception and (2) reasonable diligence toward reduction to practice from just before the senior party’s filing date through the junior party’s reduction-to-practice date.
- A party chargeable with diligence must account for the entire critical period; unexplained gaps in activity can defeat a diligence showing.
- Reasonable diligence requires evidence of concrete activity directed toward reduction to practice; general assertions of effort are inadequate.
- Testimonial evidence of diligence typically must be corroborated by independent evidence, and lack of corroborated detail may support an adverse priority determination.

## Conclusion

The court affirmed the priority award to the senior party because the junior party, though alleging earlier conception, did not carry the burden under § 102(g) to account for the entire critical period with sufficiently specific and corroborated proof of reasonable diligence toward reduction to practice.


Gould v. Schawlow, 363 F.2d 908 (C.C.P.A. 1966)