Liability and damages are proved separately. Winning the first guarantees nothing about the second.
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The most under-appreciated risk in an intellectual property case is that the infringement case succeeds and the damages case does not survive to reach a jury. Courts have been reminded, through an amendment to the rule governing expert testimony and through a run of appellate decisions, that admitting expert opinion is a gatekeeping decision requiring the proponent to establish that each step rests on sufficient facts and reliable method. In damages, that scrutiny concentrates on inputs rather than on models: whether the licenses relied on establish what they are said to establish, whether the base connects causally to the accused functionality, whether an apportionment was performed at all. The remedy when it fails can be severe — where no admissible evidence supports a royalty, an award can be reduced to a nominal sum after infringement has already been found.
The recurring grounds, in roughly the order they appear in recent decisions.
An agreement said to establish a rate it does not unambiguously establish, particularly with lump sums.
A portfolio license or a multi-feature product used without separating out the asserted patent’s contribution.
A royalty base chosen without showing why it tracks the accused functionality.
Generic starting rates and mechanical splits untethered to the facts, long since rejected.
Adjustments and conclusions resting on the expert’s say-so rather than on a traceable basis.
An opinion stated more confidently, or more broadly, than the method applied can actually support.
How the risk is reduced, in the order the work should happen.
Whether winning the case means recovering anything.
In a 2025 appellate decision the exclusion of a damages expert — for relying on a portfolio license without apportioning the asserted patent from the others in it — left a jury award of roughly ten million reduced to a single dollar. Infringement was not the problem. The record underneath the number was.
Two things reinforcing each other. The rule governing expert testimony was amended at the end of 2023 to make explicit that the proponent must establish admissibility by a preponderance and that an opinion must reflect a reliable application of the method to the facts — clarifying rather than raising the standard, but correcting a drift toward treating these as weight-not-admissibility questions. Appellate decisions since have applied that gatekeeping seriously in damages, where the inputs are frequently the softest part of an otherwise rigorous analysis.
No, and it is worth being accurate about this rather than alarmist. A 2026 appellate decision reversed a district court’s exclusion of a damages expert, holding that a usage-based royalty base did establish a sufficient causal connection to the accused functionality. The direction is toward demanding a real evidentiary connection, which cuts against opinions that assume one and in favor of opinions that demonstrate one. That is a quality standard rather than a presumption against damages testimony.
Sometimes, and the outcomes are unforgiving. Where other admissible evidence supports a royalty, a fact-finder may still award damages, and courts have occasionally allowed a further attempt. Where the record contains nothing else, the outcome can be nominal despite established infringement. Because the answer depends heavily on what independent evidence exists, the practical protection is not to let the entire damages case rest on one input.
Far earlier than it usually is — at the pleading and early discovery stage, not when the expert report is drafted. Almost everything that causes exclusion is knowable at the outset: what the license portfolio contains, whether component-level revenue exists, whether usage data is collected, whether the accused feature can be isolated. Discovering at expert disclosure that the necessary evidence was never requested is the expensive version, and by then the schedule rarely permits a fix.
Describe the damages theory and what supports it. The Institute will help you see where it is exposed.