Prior to the Federal Circuit granting Google’s petition for rehearing en banc of the panel decision in EcoFactor v. Google, 21 third parties filed amicus briefs. Rarely do patent damages issues garner such attention.

Major technology companies submitted amicus briefs. Some submitted the briefs individually, others through joint filings. Many others appeared as signatories to briefs submitted by trade groups and professional associations. Professors, interest groups, and organizations from across the ideological spectrum also submitted briefs. The filings varied in scope: some addressed a broad range of patent damages issues, while others focused on narrower, more targeted concerns.

Collectively, the amicus briefs totaled over 700 pages and cited at least 250 case precedents, 80 academic and news articles, extensive portions of the U.S. Code, numerous provisions of the Federal Rules of Evidence and Civil Procedure, legislative history, court rules, treatises, dictionaries, and congressional records.

The amicus briefs offered opposing viewpoints on several important patent damages issues that extended beyond the specific question the Court agreed to consider en banc. These contrasting views help practitioners anticipate and address likely objections to future damages opinions.

How We Got Here: A Short Summary of EcoFactor v. Google

In January 2020, EcoFactor sued Google in the Western District of Texas, alleging that Google’s Nest thermostats infringed certain EcoFactor’s patents related to smart home energy-management technology.

EcoFactor also filed infringement suits against several companies in addition to Google, including Daikin, Schneider Electric, and Johnson Controls, with whom it reached early settlements.

The confidential settlement agreements with Daikin, Schneider Electric, and Johnson Controls — which would later be referenced by EcoFactor as comparable agreements in its damages case against Google — required each licensee to make a lump-sum payment to EcoFactor. These “Reference Agreements” also included a per-unit rate in the “whereas” clauses in apparent justification for the lump-sum payment.

The expert opinion supporting EcoFactor’s damages for Google’s alleged infringement calculated damages by multiplying the number of allegedly infringing Google Nest thermostats (the royalty base) by a per-unit amount (the royalty rate). The per-unit amount for Google was based on the per-unit rates included in the whereas clauses of the Reference Agreements. EcoFactor’s expert testified that this per-unit rate reflected the royalty EcoFactor and Google would have agreed to in license negotiations, and thus was an appropriate benchmark for calculating damages.

Google challenged the admissibility of this opinion in its pretrial motions on several grounds. Google argued that: (1) Because “whereas” clauses are not binding, EcoFactor lacked sufficient factual support to represent that the parties actually agreed to the per-unit rates; (2) EcoFactor failed to establish that the Reference Agreements, as settlement agreements, were comparable to the hypothetical license between EcoFactor and Google; and (3) EcoFactor did not properly adjust for the fact that the Reference Agreements covered EcoFactor’s entire patent portfolio — not just the asserted patents — so that, in other words, EcoFactor had failed to adequately apportion damages.¹

After considering these arguments, the trial Judge denied Google’s motion in limine to exclude EcoFactor’s damages expert, although without an explanation for its decision. The case proceeded to a six-day jury trial, after which the jury found that Google had infringed, and they awarded EcoFactor $20 million in damages.

Google filed motions for a new trial over the admission of EcoFactor’s damages opinions, which the trial Court denied.

Google then appealed the case to the Federal Circuit, where it argued that the trial Court had abused its discretion in admitting EcoFactor’s damages opinion, repeating the reasons discussed above.

Ruling against Google, the three-judge Federal Circuit panel affirmed the trial Court’s decision, finding the expert’s methodology “sufficiently reliable for admissibility.” The panel reasoned that the per-unit rates in the whereas clauses reflected EcoFactor’s view of how the lump-sum payments were calculated and that EcoFactor adequately addressed differences between the Reference Agreements and the hypothetical license. It said that Google’s objections went to the weight, not admissibility.

However, one of the panel’s three judges, Judge Prost, dissented with the panel majority’s decision on damages, agreeing with Google’s that the District Court abused its discretion by admitting testimony that relied on “self-serving” whereas clauses. Judge Prost also agreed with Google that EcoFactor had failed to properly apportion because the Reference Agreements licensed EcoFactor’s entire patent portfolio, not just the asserted patents, and it failed to reliably adjust for this fact.

Google requested en banc review, which the Federal Circuit granted, but in doing so said it would only consider one of the issues in Google’s appeal: whether the District Court failed to adhere to 702 and Daubert “in its allowance of testimony from EcoFactor’s damages expert assigning a per-unit royalty rate to the three licenses in evidence.”

The en banc Court held a hearing on March 13, 2025, and on May 21, 2025, it ruled in favor of Google, reversed the district court’s denial of Google’s motion, and remanded the case for a new trial on damages.

The Amici

• In support of Google: Apple, Askeladden, Atlantic Legal Foundation, Cisco, Amici Intel et al.,² Lawyers for Civil Justice, Amici Medtronic et al.,³ Samsung, Patent Law Professors,⁴ Amici SAS et al.,⁵ Unified Patents and Amici US*MADE et al.⁶
• In support of EcoFactor: U.S. Startups & Inventors Alliance for Jobs,⁷ and Amici Professor Michael Risch et al.⁸
• In support of neither party: Licensing Executive Society USA/CAN, American Intellectual Property Law Association, Inventors Defense Alliance, Intellectual Property Owners Association, and Uber.⁹

Stout has detailed summaries of each of these briefs that can be provided upon request. Those interested can contact Bill Miras.

Themes of the Amicus Briefs

The Google amici argued that failing to address unreliable damages testimony threatens due process and leads to protracted litigation and excessive jury verdicts. In their view, such results ultimately distort the licensing market, undermine public confidence in the jury system, act as a tax on consumers, and divert resources away from innovation.

EcoFactor amici argued that failure to affirm the panel decision could further facilitate what they perceive as theft of intellectual property by some of the world’s most powerful companies.

Jury Judgment vs. Judicial Gatekeeping

The Google amici’s briefs expressed skepticism of a jury’s ability to critically assess the reliability of expert testimony.¹⁰ They cautioned that the tendency of expert testimony to take on an air of “mystic infallibility” can lead jurors to uncritically adopt damages figures presented by patentees. For this reason, one brief even advocated for disallowing the use of the term “expert” in front of the jury altogether.

The Google amici further argued that district courts, who are supposed to be the “primary enforcers” of expert reliability, all too often “punt” their gatekeeping responsibility by improperly treating reliability challenges as issues of weight rather than admissibility. In their view, the “system needs a reset” because “loose applications of Rule 702 and Daubert have allowed damages to balloon in ways that are unconnected” to the invention, infringement, and the marketplace. Ultimately, the Google amici press the en banc Court for a ruling that favors stronger judicial gatekeeping.

Google amici also encouraged the en banc Court to limit the use of certain practices they allege patent owners employ that they say inflate licensing demands and litigation damages.

These allegedly questionable practices include:

1. Entering into low-dollar lump-sum license agreements with smaller players whose low sales volumes yield high implied per-unit royalty rates, which are then used to justify disproportionately large damages claims against high-volume players
2. Intentionally making inflated “real-world” royalty-rate offers to skew the royalty rates that would, hypothetically, be used in a negotiation between the patent owner and the alleged infringer
3. Adding non-operative clauses to licenses and later recasting them as evidence of patent value
4. Relying on unverifiable, one-sided employee testimony to develop a record of self-serving past licensee positions and settlement terms

Google amici insisted that self-interested or unverifiable data should be excluded as unreliable at the Daubert stage, proposed licenses should receive little weight, and courts should exclude expert opinions grounded in “whereas” clauses or unilateral, non-negotiated assertions from patentees.

The EcoFactor amici argued that both district and appellate courts should defer to the jury once an expert’s testimony meets Rule 702’s admissibility standards and not “reweigh the facts.” They emphasized that Daubert “does not permit a district court (or an appellate court) to reject an opinion it simply may disagree with” and that the appropriate remedy for questionable expert evidence is “vigorous cross-examination, not second guessing by an appellate court.” In the EcoFactor amici’s view, the constitutional right to a trial by jury is threatened if courts wade too far into factual disputes.

Most of the neutral amici also cautioned against “overly rigid admissibility standards” and emphasized that Daubert and Rule 702 are intended as “safeguards against unreliable or irrelevant opinions, not guarantees of correctness.” They asserted that the remedy for questionable (but admissible) expert testimony is cross-examination, countervailing evidence, and careful jury instructions — not preemptive exclusion.

Neutral amici also posit that because questions of reliability are case specific, they cannot be reduced to a rigid formula, and accordingly, substantial deference should continue to be afforded to the District Court’s judgment in matters involving the admissibility of expert testimony. They urged the en banc Court to craft a decision that preserves the trial judge’s role in excluding unreliable expert testimony without imposing “an unjustified heightened burden on patentees.”

Some neutral amici downplayed the Google amici’s concerns regarding questionable practices by patent owners. For example, they argued that even if Google is correct and the royalty rate in an agreement’s recitals only reflect the patentee’s beliefs, that belief would still be relevant to the analysis of the hypothetical negotiation.

They also stated that experts are not (and should not) be required to present all their supporting data to the jury as long as they considered the data in their opinions.

Last, some of the neutral amici argued that Google’s objection — that the testimony of company witnesses should be viewed as biased when not otherwise corroborated with data — goes to witness credibility, which is for the jury to assess rather than the court.

Built-in Apportionment

Apportionment is a central theme across many of the Google amici’s briefs. In general, they argue that courts should require experts to provide more support for their apportionment opinions, particularly when the allegedly comparable licenses they rely on contain many unasserted patents. They argue that experts should not only be required to acknowledge differences in comparable licenses but should also be required to explain and calculate how variations between agreements impact the payment amounts.

EcoFactor’s amici argued that built-in apportionment should be presumed reliable when licenses are negotiated by sophisticated parties, even if they cover broad portfolios. They emphasized that breaking out value on a per patent basis is often unrealistic and that courts should respect commercial realities rather than impose rigid requirements. Disputes over apportionment, they said, are best addressed through cross-examination, not exclusion, so long as Rule 702’s reliability threshold is met.

Recasting Royalty Structures

Google’s amici argued for a higher bar when experts recast lump-sum payments from license agreements into a running royalty structure for damages.¹¹

They argued that lump-sum and running-royalty structures fulfill distinct business purposes and should not be assumed as interchangeable. Some of the factors they argued that influence license structure include:

1. The size and merits of the patent portfolio
2. The type and volume of products involved
3. The features allegedly implicated by the patents
4. Comparable licenses and litigation risks
5. The value of “patent peace” or freedom to operate
6. Other benefits conveyed, including business relationships or asset sales

Google amici also argued that merely acknowledging differences between licenses is not enough and that experts must quantify the differences, use actual sales data, and “demonstrate to the trial judge how the [royalty structure] conversion was done, [by] both describing the method and doing the math.”

In contrast, EcoFactor amici argued that running royalty rates derived from lump sum agreements do not always need to be verified, or corroborated, using actual sales data, noting that “it is a common fact of litigation that a corporate officer [of the licensor] would not be provided privileged access to [the licensee’s] sales data.”

Certain neutral amici agreed with EcoFactor, stating that requiring a plaintiff to support its comparable license analysis with licensee sales data would be unreasonable and “impair accuracy and impose needless burdens” on licensors. They argued that it is common for a licensor to state its understanding of the licensed rate in an agreement where the licensee did not, or would not, disclose its actual sales data to the licensor but instead represented, or stipulated, its sales data verbally to the licensor as part of the negotiations.

Use of Unquantified Royalty Rate “Pressures”

Google amici urged the Court to more closely scrutinize expert opinions that rest upon unquantified “upward” or “downward” royalty pressures, arguing that such vague assertions undermine the reliability of the damages opinion. They argued that no weight should be given to damages opinions that include such improper “fact-agnostic hand-waving.”

These amici urged the Court to reject “generic qualitative assertions of ‘upward’ or ‘downward’ pressure,” warning that allowing this improperly permits damages experts to “evade scrutiny” and bypass proper apportionment. They insisted that experts must be required to justify royalty rates “with math, not unquantified ‘up’ and ‘down’ arrows.” They characterize such “upward” adjustments as so speculative that they could justify apportionment in any case.

The EcoFactor amici argued that unquantified royalty rate pressures can be a legitimate part of expert damages testimony, emphasizing that not all economic influences in licensing can or should be reduced to precise numerical values. They cautioned against rigid admissibility standards that would exclude such testimony, asserting that qualitative factors often reflect real-world licensing dynamics. According to these amici, concerns about vagueness should be addressed through cross-examination rather than exclusion under Daubert as long as the expert’s methodology satisfies Rule 702’s reliability requirements.

Takeaways and Looking Ahead

The debate among the numerous amici in EcoFactor centers on whether and to what extent damages testimony should be subject to stricter judicial gatekeeping and heightened evidentiary standards. Google’s amici advocated for stricter admissibility standards and greater judicial gatekeeping, seeking more quantifiable damages opinions based on objective evidence and the exclusion of unverifiable data. Conversely, EcoFactor’s amici and many neutral amici emphasized preserving the jury’s fact-finding role and cautioned against overly rigid standards that they argue would unfairly burden patentees.

Given the Court sided with Google and has adopted slightly stricter evidentiary standards for comparable licenses, parties will likely face expanded discovery obligations to substantiate damages claims. Accordingly, many existing license agreements may struggle to withstand judicial scrutiny as reliable benchmarks for litigation damages opinions.

By advocating a stricter standard, the Google amici may have inadvertently hindered defendants as well — those who cite lump-sum agreements without accompanying licensee data may encounter similar admissibility hurdles. At least one amicus, however, appears to recognize this potential issue, and addresses it by arguing that prior agreements should still be allowed defensively, even if insufficient for offensive use under the proposed framework.

Accordingly, going forward in certain industries, technologies, and licensing contexts, parties may increasingly memorialize the nature of how lump sum payments were calculated, either explicitly within the license agreement itself or through an appended document or maintain more detailed records of corroborating evidence for use in litigation. 

In sum, the split among the amici reinforces the strategic value of proactively identifying and addressing potential vulnerabilities in a damages case that opponents can target. It may become even more important for parties involved in litigation to consider the benefits of identifying damages issues, conducting supporting research, and tailoring discovery requests to the facts of their case as early as possible.

This was previously published in Law360.

1. Apportionment in a patent litigation context refers to the process of identifying and separating the portion of a product’s value or profits that is attributable specifically to the patented invention as opposed to unpatented features or other components.
2. Amici Intel et al. include Intel Corporation, Dell Inc., Motorola Mobility LLC, and Western Digital Corporation; Intel and Dell filed another amicus brief separate from Motorola Mobility LLC and Western Digital Corporation.
3. Amici Medtronic et al. include Medtronic PLC et al. and Advanced Medical Technology Association.
4. Submitted by patent and evidence law professors Jeremy W. Bock, Michael Carrier, Bernard Chao, Jorge L. Contreras, Thomas F. Cotter, Charles Duan, Paul R. Gugliuzza, Amy Landers, Mark A. Lemley, Brian J. Love, Jane Campbell Moriarty, Jason Reinecke, Joseph Sanders, and Joshua D. Sarnoff.
5. Amici SAS et al. include SAS Institute Inc., Symmetry, LLC, SAP America, Inc., Garmin International Inc., Vizio, Inc., ACT | The App Association, Tesla, Inc., Software & Information Industry Association, and Red Hat, Inc.
6. Amici US*MADE et al. include U.S. Manufacturers Association for Development and Enterprise (“US*MADE”), National Retail Federation, Computer & Communications Industry Association, and Public Intertest Patent Law Institute.
7. New Civil Liberties Alliance (NCLA) also filed an amicus brief in support of EcoFactor. The brief argues that the en banc court rehearing the case is improperly constituted because it excludes Judge Newman, who remains in “regular active service” and has not recused herself. They contend that, under 28 U.S.C. § 46(c), an en banc court must include all such judges, and failing to do so renders the tribunal unlawful. Because the NCLA brief does not address any damages issue, I do not discuss it further.
8. Amici Professor Michael Risch et al. include Professors Michael Risch, Aisha Mahmood Haley, Austin Curry, Brad W. Caldwell, Jason D. Cassady, Hamad M. Hamad, and James F. Smith.
9. Uber’s brief generally argues that infringer’s profits should rarely be considered in a reasonable royalty analysis, because in their view they reflect more than just the patent and are influenced by other factors like marketing and branding.
10. While not all Google amici address, or agree, on every issue, we generally attribute the different positions to the entire group for convenience purposes only. We do the same for the other two groups of amici.
11. A lump sum structure provides a predetermined payment amount for unlimited use of the licensed technology. A running royalty involves payments for ongoing use of the technology, such as a percentage of apportioned revenues from licensed product sales or a per-unit amount for each licensed product sold.