In patent infringement cases, prevailing on liability is only half the battle. The damages award depends on the rigor and credibility of the underlying financial analysis, which receives the same level of scrutiny as the legal arguments themselves. An opinion that cannot withstand cross-examination or a Daubert challenge can undermine an otherwise strong case.
Under 35 U.S.C. § 284, courts recognize lost profits and reasonable royalties as the two primary remedies in patent infringement cases. Each carries distinct evidentiary requirements and methodological standards. This post walks through the legal frameworks governing both, what valuation experts are expected to demonstrate, and how the quality of that analysis can determine trial outcomes.
The Legal Foundation: What Courts Expect in Patent Damages
35 U.S.C. § 284 establishes the statutory basis for patent damages, requiring that the award be “adequate to compensate” the patentee for the infringement, with a floor of no less than a reasonable royalty. The statute does not cap damages, but it requires that they be grounded in evidence.
The burden falls on the patentee to prove damages with reasonable certainty. Panduit Corp. v. Stahlin Bros. Fibre Works, 575 F.2d 1152 (6th Cir. 1978) remains the foundational precedent establishing the framework for lost profits analysis. Courts have built on that foundation over decades, and damages experts are expected to align their methodology with established legal standards from the outset.
Expert reports are evaluated under Daubert v. Merrell Dow Pharmaceuticals, 509 U.S. 579 (1993), which requires that expert testimony be based on sufficient facts, derived from reliable principles and methods, and properly applied to the facts of the case. Speculative analysis, unsupported assumptions, or methodological shortcuts are grounds for exclusion, and exclusion of a damages expert at this stage can be case-dispositive.
Calculating Lost Profits in Patent Infringement Cases: The Panduit Test
Lost profits represent the revenue the patentee would have earned but for the infringement. Panduit established a four-factor test that remains the operative standard for proving this type of damage.
To recover lost profits, the patentee must demonstrate: (1) demand for the patented product; (2) the absence of acceptable non-infringing alternatives; (3) the manufacturing and marketing capability to exploit that demand; and (4) the amount of profit the patentee would have made.
Each factor requires evidentiary support. Demand is typically established through sales data and market documentation. The absence of non-infringing alternatives requires an analysis of competing products and whether they would have captured sales in the patentee’s absence. Capability is demonstrated through capacity documentation and operational records. Profit is calculated on an incremental basis, meaning revenue minus incremental costs, rather than using fully allocated overhead, which tends to understate margin.
Common vulnerabilities that weaken lost profits claims include failure to identify and account for non-infringing alternatives, overstated market-share assumptions, and reliance on fully absorbed cost structures rather than incremental margins. Opposing experts routinely target these areas, and courts have excluded opinions that rely on them.
The “But For” Standard
The hypothetical construct underlying lost profits analysis is the “but for” world: what would the patentee have earned absent the infringement? This requires a reconstruction of market conditions grounded in actual data, not projections built on simplified competitive assumptions. Courts have excluded opinions that rely on speculative projections or ignore relevant market dynamics.
Rite-Hite Corp. v. Kelley Co., 56 F.3d 1538 (Fed. Cir. 1995) addressed the scope of compensable lost profits and expanded its reach in one important respect. The court held that lost profits can extend to directly competing products not covered by the patent in suit, provided the losses were reasonably foreseeable and causally linked to the infringement. At the same time, the court drew a firm boundary, vacating the dock leveler damages specifically because those products did not functionally operate with the patented invention. The causal link required to support a lost profits claim must be grounded in how the products actually interact in the market, not merely in the competitive relationship between the parties.
Calculating Reasonable Royalties: The Georgia-Pacific Framework
When lost profits cannot be proven in full, 35 U.S.C. § 284 establishes a reasonable royalty as the minimum floor for damages. In practice, reasonable royalties are the more commonly litigated remedy, and they are also the one where expert methodology is most frequently challenged.
Georgia-Pacific Corp. v. U.S. Plywood Corp., 318 F. Supp. 1116 (S.D.N.Y. 1970) introduced the fifteen-factor framework that courts continue to apply. The framework centers on a hypothetical negotiation between a willing licensor and a willing licensee, conducted on the date infringement began and with the assumption that both parties knew the patent was valid and infringed.
The most analytically significant factors include the existence of comparable license agreements, the commercial relationship between the parties, the established royalty for the patent, if any, and the portion of profit attributable to the patented invention, distinct from other elements of the product. Not every factor will be relevant in every case, but experts are generally expected to address the full framework and explain which factors drive their opinion.
The Hypothetical Negotiation
The hypothetical negotiation is not a theoretical exercise. It must be grounded in the commercial realities of the parties’ relationship and the relevant market at the time infringement began.
Comparable licenses are the most persuasive evidence in this analysis, but they must be sufficiently similar in scope, technology, and economic context to be probative. Courts have rejected royalty opinions built on loose analogies. In Uniloc USA, Inc. v. Microsoft Corp., 632 F.3d 1292 (Fed. Cir. 2011), the Federal Circuit held that the 25% rule of thumb has no place in a reasonable royalty analysis because it is untethered to the facts of any particular case. That decision reinforced the standard that the royalty rate must be derived from evidence specific to the matter at hand.
Apportionment is equally critical. Expert opinions must isolate the value attributable to the patented feature and separate it from unpatented components. In VirnetX Inc. v. Cisco Systems, 767 F.3d 1308 (Fed. Cir. 2014), the Federal Circuit vacated the damages award because the expert’s royalty base was not properly apportioned to the infringing features. The opinion applied a royalty to a broader revenue base than the evidence supported, and the court found that legally insufficient.
Why the Quality of Valuation Analysis Determines Outcomes
A damages opinion is only as strong as its underlying data, assumptions, and documentation. Opposing experts will examine every variable, and the court will apply the same scrutiny through the Daubert lens.
Weaknesses in methodology are a primary target at the Daubert stage. An opinion that uses an unsupported royalty base, ignores relevant market evidence, or applies a generic framework without tethering it to the specific case is vulnerable to exclusion. When a damages expert is excluded, the patentee may have no path to a damages award at all, which can effectively end a claim or force a settlement on unfavorable terms.
According to the Reference Manual on Scientific Evidence, 4th ed. (2025), published by the National Academies of Sciences, Engineering, and Medicine and the Federal Judicial Center, courts expect expert opinions to be grounded in sound methodology and applied with intellectual rigor. The American Bar Association’s Understanding IP Damages, Part 2: Patent Law (2025) similarly underscores the importance of aligning damages methodology with the governing legal standards before the expert report is finalized.
The independence of the valuation firm also matters. Unlike firms where valuations are an ancillary service offered alongside audit, tax, or investment banking, a pure-play appraiser has no institutional interest in reaching a particular outcome. In litigation, where the credibility of a damages opinion is scrutinized by opposing counsel, judges, and juries, that independence translates into an objectivity that firms with competing service lines structurally cannot offer.
The Financial Case Behind Every Patent Verdict
Damages in patent infringement cases are not a back-of-the-envelope calculation. Courts expect methodologically sound, well-documented expert analysis built on established legal frameworks, and the record reflects how often cases turn on whether that standard is met.
Whether the claim rests on lost profits or reasonable royalties, the strength of the underlying financial analysis is what separates a defensible opinion from one that gets excluded.
Attorneys and in-house counsel working on patent matters benefit from engaging a valuation expert early, before the damages theory is set in stone and before strategic decisions are made that depend on an accurate read of the financial exposure.
Appraisal Economics has supported patent infringement litigation across a range of industries, providing lost profits analyses and reasonable royalty opinions that meet Daubert standards and hold up under cross-examination. Our team includes CFAs, ASAs, and financial experts with deep experience in Intellectual Property Valuations, and our independence as a pure-play firm means our opinions are never shaped by anything other than the facts of the case. To discuss your matter, contact our team directly or learn more about our patent valuation services.