Human Factors Expert’s Testimony on Dark Patterns Excluded

The Federal Trade Commission contended that Amazon tricked, coerced, and manipulated consumers into subscribing to Amazon Prime. According to the FTC, this was accomplished by failing to disclose the material terms of the subscription clearly and conspicuously and by failing to obtain the consumers’ informed consent before enrolling them. The FTC also alleged that Amazon did not provide simple mechanisms for subscribers to cancel their Prime memberships. The FTC sued Amazon.com, Inc. and three of the company’s executives, Neil Lindsay, Russell Grandinetti, and Jamil Ghani.

Defendants’ expert Craig Rosenberg‘s opening report addresses the FTC’s allegation that Amazon used deceptive practices known as “dark patterns” in user interface design to drive unintended Prime membership.

Rosenberg’s opening report makes several findings. He stated that there is ambiguity in the definition of the term “dark patterns,” it is difficult to measure clarity in user experience design and subjective evaluations are insufficient to measure this clarity, Amazon’s initiatives to enhance clarity demonstrate a commitment to data-driven user experience refinement, Amazon uses empirical evidence to inform design decisions, there are alternative (non-user experience design) explanations for declines in Prime membership subscriptions following clarity-centered changes, and the absence of objective standards for clarity risks penalizing legitimate business practices. 

The FTC filed a motion to exclude Rosenberg’s testimony on three grounds. First, it said that his methods are unexplained and unreliable. Second, it said that he is not qualified to testify on the subject of his opinions. And third, it said that his testimony is irrelevant and confusing.

Human Factors Expert Witness

Craig S. Rosenberg, Ph.D., is a consultant who provides advanced engineering services for a wide array of companies. He has a Master of Science and Ph.D. from the University of Washington in Human Factors, a multidisciplinary field that studies how people interact with machines, technology, and their environment. 

Want to know more about the challenges Craig Rosenberg has faced? Get the full details with our Challenge Study report.

Discussion by the Court

Rosenberg’s opening report, rebuttal report, and deposition testimony all indicate the primary source of his expert opinions is his experience, training, and education as a human factors engineer. However, Rosenberg’s inability to articulate how his education, training, and experience have led him to his conclusions shows that these conclusions are not the product of a reliable method; therefore, the Court held that his testimony is inadmissible.

Amazon said Rosenberg’s “references to the ‘totality’ of his experiences are not evasions, but acknowledgments that his expert conclusions stem from integrated professional judgment based on decades of interface design.” Even so, Rosenberg must explain how his decades of experience inform his expert conclusions. By his own admission, he cannot do so.

Held

The Court granted Plaintiff FTC’s Rule 702 motion to exclude the testimony of Defendants’ expert Craig Rosenberg.

Key Takeaway:

Liberally construing Rule 702 in favor of admissibility, Rosenberg’s opinion does not show how his experience informs his conclusions. He draws no methodological nexus between his conclusions and his experience, education, and training, other than to say his conclusions are based on his experience, education, and training. This circular reasoning is insufficiently reliable.

Case Details:

Case Caption:	Federal Trade Commission V. Amazon.Com, Inc., Et Al.
Docket Number:	2:23cv932
Court Name:	United States District Court, Washington Western
Order Date:	August 11, 2025