## Facts

- Multiple consolidated patent and antitrust actions involved false-twist machines and processes for texturizing synthetic yarn.
- Duplan, a yarn “throwster,” alleged Sherman Act §§ 1–2 violations based on practices that allegedly restricted access to unlicensed, royalty-free false-twist machines.
- Duplan also sought declarations that numerous patents held by Chavanoz were invalid, unenforceable, and not infringed, asserting patent misuse and inequitable conduct.
- Duplan sought discovery of materials created in earlier, terminated litigation involving Chavanoz, including attorney analyses connected to settlement agreements and evaluations of prior art and patent validity.
- The requested materials included documents reflecting attorneys’ mental impressions, conclusions, opinions, and legal theories formed during the earlier litigation.

## Issues

1. Whether attorney opinion work product created in earlier, terminated litigation is discoverable in subsequent litigation.
2. How Rule 26(b)(3) distinguishes “opinion” work product from non-opinion (ordinary) work product for discovery purposes, including in later litigation.

## Decision

- The Fourth Circuit vacated the district court’s discovery order and remanded.
- The court held that attorney opinion work product remains immune from discovery even after the litigation in which it was created has terminated.
- The court directed that, on remand, discovery must be limited so as to protect materials revealing attorneys’ mental impressions, conclusions, opinions, or legal theories.
- The court recognized that non-opinion work product may be discoverable only under the Rule 26(b)(3) standards, but the district court’s order failed to separate protected opinion materials from other materials.

## Legal Principles

- Under Fed. R. Civ. P. 26(b)(3), courts must protect against disclosure of an attorney’s mental impressions, conclusions, opinions, or legal theories concerning litigation.
- Opinion work product receives a higher level of protection than ordinary work product; it is generally not subject to discovery even where relevance and need are asserted.
- The protection for opinion work product does not lapse merely because the earlier litigation has ended.
- Ordinary work product (materials not revealing attorney thought processes) may be discovered only upon a showing of substantial need and inability to obtain the substantial equivalent without undue hardship.

## Conclusion

The Fourth Circuit held that opinion work product created in prior, terminated litigation remains immune from discovery in later litigation, vacated an overbroad production order, and remanded for discovery proceedings that protect attorney mental impressions and legal theories while applying Rule 26(b)(3) to any non-opinion materials.


Duplan Corp. v. Moulinage & Retorderie de Chavanoz, 509 F.2d 730 (4th Cir. 1975)