## Facts

- Aukerman owned patents covering slip-form methods and devices for forming asymmetrical concrete highway barriers.
- After earlier litigation, Aukerman licensed a slip-form manufacturer that agreed to notify Aukerman of purchasers of adjustable slip-forms.
- After receiving notice that Chaides purchased a slip-form, Aukerman’s counsel sent letters in 1979 asserting possible infringement and offering a license; communications included an offer to waive past infringement in exchange for a license, which Chaides declined.
- Following the 1979 exchanges, there was an approximately eight-year period without communication.
- Chaides later developed a second slip-form mold that Aukerman also believed infringed.
- After renewed, unsuccessful licensing discussions, Aukerman sued Chaides for patent infringement in 1988.
- The district court granted summary judgment to Chaides based on laches and equitable estoppel.

## Issues

1. Whether laches is an equitable defense in patent infringement actions under 35 U.S.C. § 282, and what elements and presumptions govern it.
2. Whether equitable estoppel is an equitable defense under 35 U.S.C. § 282, and what elements govern it in the patent context.
3. Whether, under the correct standards, laches or equitable estoppel barred Aukerman’s claims as a matter of law on summary judgment.

## Decision

- The Federal Circuit (en banc) held that both laches and equitable estoppel are cognizable defenses under 35 U.S.C. § 282.
- The court articulated governing elements and clarified burdens and the effect of presumptions.
- The court ruled that the district court used incorrect legal standards and that genuine disputes of material fact existed as to both defenses.
- The court reversed the summary judgment for Chaides and remanded for further proceedings.

## Legal Principles

- Laches in patent cases requires: (1) unreasonable and inexcusable delay in bringing suit; and (2) material prejudice to the accused infringer resulting from the delay.
- If the patentee knew or should have known of the accused activity and delayed more than six years, a presumption of laches arises; the presumption shifts only the burden of production, not the ultimate burden of persuasion, which remains on the accused infringer.
- Material prejudice for laches may be evidentiary (e.g., loss of proof) or economic (e.g., investments made during the delay).
- Equitable estoppel requires: (1) misleading conduct by the patentee causing a reasonable inference that the patent will not be enforced; (2) reliance by the accused infringer; and (3) material prejudice if the patentee proceeds.
- Misleading conduct may consist of statements, actions, inaction, or silence where there is an obligation to speak; whether silence is misleading depends on the full course of dealings.
- Laches generally limits recovery of pre-suit damages, while equitable estoppel can bar all relief, including damages and injunctive relief.
- Summary judgment on these equitable defenses is improper when disputed facts exist regarding the reasonableness of delay, prejudice, misleading conduct, or reliance.

## Conclusion

The en banc Federal Circuit confirmed laches and equitable estoppel as patent defenses under § 282 and set out their elements, burdens, and the six-year laches presumption; it reversed summary judgment because disputed facts remained as to whether Aukerman’s delay and conduct satisfied either defense.


A.C. Aukerman Co. v. R.L. Chaides Constr. Co., 960 F.2d 1020 (Fed. Cir. 1992) (en banc)