Federal Circuit Clarifies When Non-Infringing Products Can Form Part of a Royalty Base

Why It Matters

The ruling expands the scope of recoverable damages, giving patent owners a viable path to include related economic activity while forcing defendants to defend broader royalty‑base theories. It will influence litigation strategy and discovery practices across the tech sector.

Key Takeaways

• Federal Circuit reversed exclusion of Exafer's damages expert opinion
• Court allowed VM‑hour revenue as royalty base linked to patents
• Decision distinguishes Enplas precedent, permitting non‑infringing products with causal link
• Patent owners must document technical nexus to support expanded royalty bases
• Defendants should aggressively seek discovery on alleged non‑infringing economic activity

Pulse Analysis

Patent damages hinge on two variables: the royalty rate and the royalty base. While courts have long required that the base reflect value attributable to the infringing features, the line between infringing and ancillary products has been blurry. The Federal Circuit’s Exafer decision clarifies that non‑infringing items may be included when a demonstrable causal connection exists—specifically, when the patented invention directly drives additional sales or usage of those items. By anchoring the royalty base to incremental VM‑hour revenue, the court affirmed that economic spillovers tied to a patent can be monetized, provided the link is substantiated with technical and financial evidence.

The opinion departs from the *Enplas* precedent, which barred royalty bases lacking any causal nexus to the accused product. Exafer’s expert showed that Microsoft’s patented network‑optimization features allowed more VMs per CPU, generating extra VM‑hour sales. The court found Microsoft’s own documents corroborated this link, thereby satisfying the “reasonable royalty” requirement of 35 U.S.C. §284. This nuanced approach signals that courts will scrutinize the factual underpinnings of any expanded base rather than applying a categorical rule, encouraging more rigorous expert analyses and detailed evidentiary records.

For practitioners, the decision translates into actionable steps. Patent owners should begin early collection of internal performance data, engineering reports, and market analyses that tie patented functionality to downstream revenue streams. Simultaneously, they must be prepared to defend the relevance of that data against accusations of fishing. Defendants, on the other hand, can leverage the ruling to demand granular discovery on the plaintiff’s alleged causal connections, potentially narrowing the royalty base or prompting a settlement. As technology ecosystems grow more interdependent, the ability to convincingly link a patent’s contribution to ancillary products will become a decisive factor in high‑stakes infringement cases.