## Facts

- DuPont owned U.S. Patent No. 3,063,189 covering a monofilament fishing line containing fluorescent dye.
- The patent claimed the line would be highly visible above water because ultraviolet light would activate the dye, but relatively invisible below water because water would absorb ultraviolet light.
- DuPont filed the application in January 1962, marketed the product in August 1962, and received the patent in November 1962.
- Berkley began selling fluorescent fishing line in November 1962, stopped in 1963 after receiving notice, and later resumed sales of a product DuPont alleged copied the patented line.
- Berkley admitted copying and reportedly earned more than $7.5 million from the accused product.
- Berkley challenged validity, primarily asserting lack of utility and related allegations that DuPont misrepresented or withheld material information from the Patent Office.
- Berkley presented tests suggesting the line did not reliably “glow” or deliver the claimed above-water/underwater visibility performance under various conditions.

## Issues

1. Whether the jury’s general verdict of patent invalidity (focused on utility and alleged misrepresentation) could stand given the presumption of validity and the clear-and-convincing burden.
2. Whether the district court’s jury instructions on utility and misrepresentation/fraud correctly stated the governing legal standards.
3. Whether Berkley was entitled to relief on its antitrust counterclaim and to attorney’s fees and additional costs based on DuPont’s enforcement of the patent.

## Decision

- The court reversed the judgment holding the patent invalid and remanded for a new trial limited to the issue of validity.
- The court held that errors in the handling and instruction of the validity defenses created a risk that the jury invalidated the patent without applying the proper standards.
- The court affirmed dismissal of Berkley’s antitrust counterclaim.
- The court affirmed denial of Berkley’s motion for attorney’s fees and additional costs.

## Legal Principles

- An issued patent is presumed valid; invalidity must be proven by clear and convincing evidence.
- Utility challenges must be evaluated under the correct legal standard; shortcomings in product performance evidence do not automatically establish lack of utility as a matter of law.
- A claim of fraud or inequitable conduct requires clear and convincing proof of a material misrepresentation or omission and intent to mislead the Patent Office.
- A new trial may be ordered where flawed instructions or submission of issues to the jury risks an unjust invalidity determination, and the remand may be limited to validity when appropriate.
- Antitrust liability premised on patent enforcement generally requires a showing beyond mere assertion of patent rights, including bad faith or comparable wrongful conduct.
- Attorney’s fees in patent cases require an “exceptional case” showing; absent such proof, fee shifting is unwarranted.

## Conclusion

The Eighth Circuit set aside the jury-based invalidity judgment because the utility and misrepresentation defenses were submitted under legally deficient standards inconsistent with the presumption of validity and the clear-and-convincing burden, ordered a new trial confined to validity, and left intact the rejection of Berkley’s antitrust and fee requests.


E. I. du Pont de Nemours & Co. v. Berkley & Co., 620 F.2d 1247 (8th Cir. 1980)