Copyright damages and apportionment expert
Expert class library · Intellectual property · Either side
Measures the copyright owner's actual damages, often as a lost licensing fee, and the infringer's profits that are attributable to the copied work. Because the statute allows recovery only of profits attributable to the infringement, the expert must separate profits caused by the work from those driven by other factors, and courts exclude apportionment opinions that rest on unexplained assumptions.
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Questions this testimony turns on
- What gross revenue is reasonably related to the infringement, and which revenue streams should be excluded?
- What share of the infringer's profits is attributable to the copied work rather than to other elements of the product?
- Which costs has the infringer proven are deductible from gross revenue?
- What license fee would a willing buyer and willing seller have agreed to for the use actually made?
- Did the infringement harm the market for the original work or its derivatives?
Methods
- Infringer profits apportionment
- Deductible expense analysis
- Licensing fee benchmark
- Market harm analysis
How the testimony is attacked
- Apportionment percentages without an identifiable method. Defendants argue that the expert's allocation of profits to the copied work rests on assumptions with no stated methodology. In Rearden v. Walt Disney Pictures the Ninth Circuit affirmed exclusion of the plaintiff's apportionment testimony because key assumptions lacked an identifiable methodology.
- Experience not shown to support the apportionment. Opponents challenge experts who rely on professional experience without explaining how that experience yields the specific allocation. The Rearden court also upheld exclusion because the expert did not explain how his experience qualified him to perform the apportionment analysis.
- Simplifying allocation assumptions. Plaintiffs attack apportionments that treat every customer or every line of code as contributing equally to profit, arguing some contribute far more than others. In Iconics v. Massaro the court held such assumptions went to weight because the defense expert justified the method and applied it in a defensible, replicable way.
- Revenue base not causally linked to the infringement. Defendants argue the expert used revenue too remote from the infringing use. In D'Pergo Custom Guitars v. Sweetwater Sound the First Circuit accepted that sales narrowed to customers who viewed the infringing guide could be reasonably related to the infringement.
- License fee testimony lacking industry grounding. Challengers attack actual damages opinions that do not reflect real licensing practice. The D'Pergo court found no abuse of discretion in admitting the plaintiff's photography expert, whose testimony supported the actual damages award.
What the public record shows
Courts have filed at least 6 opinions since 2015 that discuss this class of testimony and cite Daubert or Rule 702, as of October 2, 2026. Three that show how courts handle this class of testimony:
| Outcome | Case | Court | Year | Why |
|---|---|---|---|---|
| Excluded | Rearden, LLC v. Walt Disney PicturesNo. 24-3970 | 9th Cir. | 2025 | The Ninth Circuit affirmed the Rule 702 exclusion of the plaintiff's profits apportionment testimony because key assumptions lacked an identifiable methodology and the expert did not show how his experience qualified him to apportion. |
| Admitted | D'Pergo Custom Guitars, Inc. v. Sweetwater Sound, Inc.111 F.4th 125 | 1st Cir. | 2024 | The First Circuit held the district court did not abuse its discretion under Rule 702 in admitting the plaintiff's expert testimony on which the copyright actual damages award rested. |
| Admitted | Iconics, Inc. v. Massaro266 F. Supp. 3d 461 | D. Mass. | 2017 | The court refused to exclude the defendants' damages expert's apportionment of infringer profits, which assumed each customer and each line of code contributed equally, because he justified the method and applied it in a replicable way, leaving its merits for cross-examination. |
Each case links to the free opinion text on CourtListener.
In federal court: amended Rule 702
In federal court, since December 1, 2023, Rule 702 says expressly that the party offering an expert must show the court it is more likely than not that the testimony meets each requirement: that it rests on sufficient facts or data, uses reliable methods, and reflects a reliable application of those methods to the case. Questions about the basis of an opinion are no longer automatically matters of weight for the jury. For how the circuits have applied the amendment, see the Rule 702 tracker, which follows each court of appeals; for what that means for preparing or attacking this class of expert, see the guide on amended Rule 702.
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Updated October 2, 2026. How this page is built: rulings are found by searching court opinions on CourtListener. The summaries are written by AI working from the full text of each opinion, and every citation and link is checked automatically. Outcomes are labelled by what the court did with the expert’s testimony. No individual expert is named. This page summarises public decisions for orientation and is not legal advice; read the opinion before relying on any ruling. Spotted an error? Tell us.