## Facts

- Swift Agricultural Chemicals Corp. owned a patent covering a process for manufacturing liquid ammonium polyphosphate fertilizer.
- Swift previously sued Usamex Fertilizers, Inc. for infringement; after trial, the patent was held valid and infringed, and later post-judgment efforts to reopen the case were rejected.
- Swift later sued Farmland Industries, Inc.; after trial, a final judgment held the same patent invalid for anticipation.
- Before the Farmland invalidity judgment issued, Swift accused Mississippi Chemical Corp. of infringing the same patent in a separate district court action.
- After the Farmland judgment became final, Mississippi Chemical moved for summary judgment, arguing Swift was barred by defensive issue preclusion under *Blonder-Tongue* from relitigating patent validity.
- The district court denied summary judgment without requiring Swift to show why the prior invalidity judgment should not have preclusive effect.
- Mississippi Chemical petitioned the Federal Circuit for a writ of mandamus directing the district court to grant summary judgment of invalidity.

## Issues

1. Whether mandamus should issue to compel the district court to apply *Blonder-Tongue* defensive collateral estoppel based on a prior final judgment declaring the patent invalid.
2. Whether the patentee had a full and fair opportunity to litigate validity in the prior invalidity action, such that relitigation of validity is barred despite an earlier, conflicting validity judgment.

## Decision

- The Federal Circuit granted the petition for a writ of mandamus.
- The court directed the district judge to grant Mississippi Chemical’s motion for summary judgment that the patent is invalid.
- The court held that the prior final judgment of invalidity required estoppel and that the district court erred by denying summary judgment without placing the burden on the patentee to show why estoppel should not apply.

## Legal Principles

- Under *Blonder-Tongue Labs., Inc. v. Univ. of Ill. Found.*, a patentee may be barred by defensive issue preclusion from relitigating patent validity after a prior final judgment of invalidity, if the patentee had a full and fair opportunity to litigate validity in the earlier case.
- The existence of an earlier decision upholding validity does not, by itself, prevent application of estoppel once a later fully litigated case results in a final invalidity judgment.
- When a defendant shows a prior final invalidity judgment on the same patent, the patentee bears the burden to identify reasons—grounded in fairness and litigation opportunity—why preclusion should not apply.
- Mandamus may be used to correct a clear refusal to apply controlling precedent when the legal entitlement to relief is clear and the district court’s action is not within permissible discretion.

## Conclusion

Because a final judgment had already held the patent invalid after a full and fair opportunity to litigate, Swift was precluded from relitigating validity against Mississippi Chemical, and the Federal Circuit used mandamus to require entry of summary judgment of invalidity.


Mississippi Chem. Corp. v. Swift Agric. Chems. Corp., 717 F.2d 1374 (Fed. Cir. 1983)