The present action stems from Plaintiff ML Products, Inc. (“ML Products”) and Defendants BillionTree Technology USA, Inc. (“BillionTree”) and Mountain Peak, Inc. (“Mountain Peak,” collectively, “Defendants”) competing for sales on Amazon.com where Defendants allegedly employed fraudulent tactics. Specifically, ML Products asserted claims of violations of the Lanham Act, false advertising, and unfair competition against Defendants.
On April 12, 2024, Professor Brett Hollenbeck, ML Products’ affirmative technical expert, produced an expert report on his analysis of “the tactics related to online reviews used by certain competitors of ML Products, including BillionTree and its [alleged] affiliates.”
Broadly, Hollenbeck opined that 22 of the 29 products sold by BillionTree and its alleged affiliates engaged in review hijacking—inappropriately linking a different product’s reviews to the given product on Amazon and misrepresenting the product as having more positive reviews; reviewers of nine of the products complained that the seller sent them emails requesting them to change negative reviews into positive ones in exchange for payment; and by manipulating and falsifying product ratings, BillionTree increased its visibility and sales on Amazon, misled customers, and lowered the visibility of its competitors, thereby harming ML Products.
Defendants filed a motion to exclude the testimony of Hollenbeck.
Marketing Expert Witness
Prof. Brett Hollenbeck is an Associate Professor of Marketing at the UCLA Anderson School of Management in Los Angeles, California. His educational background includes a Bachelor of Science in Economics and a Bachelor of Arts in Political Science, both from the George Washington University, a Masters in Economics from the University of Texas at Austin and a Ph.D. in
Economics from the University of Texas at Austin.
Discussion by the Court
1. The Expert Report is Compliant with Rule 26(a)
Defendants argued that ML Products failed to disclose the facts and data—specifically, the Amazon information—considered by Hollenbeck in forming his opinion. Defendants further argued that ML Products’ failure to disclose warrants sanctions under Rule 37.
The Court did not find that ML Products failed to disclose the facts and data considered by Hollenbeck in forming his opinion. Although Defendants are correct that the Hollenbeck Report must lay out the factual bases for his opinions, the Hollenbeck Report provided the factual bases upon which he formed his opinions as he explored whether BillionTree and its alleged affiliates engaged in product rating manipulation to increase its sales and harm competitors like ML Products.
For instance, Hollenbeck opined that 22 of the 29 products sold by BillionTree and its alleged affiliates engaged in review hijacking; 9 of the products had reviews where customers were offered gift cards to change negative reviews into positive ones; and BillionTree and its alleged affiliates’ conduct increased their products ratings and hurt the sales of its competitors, including ML Products.
The Court is not convinced that ML Products’ disclosure prevented Defendants from conducting a meaningful deposition of Hollenbeck, as Defendants have had until August 20, 2025, to submit a rebuttal report and until September 3, 2025, to complete discovery, which is more than sufficient time.
The Court found that sanctions under Rule 37 is not warranted, as ML Products did not fail to disclose Hollenbeck as an expert witness nor the facts and data supporting his opinions in the Hollenbeck Report.
2. The Expert Report is Not Improper under FRE 703
Defendants argued that the Hollenbeck Report should be excluded because it relies on inadmissible hearsay and improperly attempts to establish the truth of its content.
However, the Court held that Hollenbeck may rely on hearsay as it is reasonably relied upon in the field of marketing academia. Typically, an academic expert in online marketplaces will review comment entries on marketplaces to identify how the products function. Further, Hollenbeck used the marketplace reviews and applied his expertise to form an independent judgment that BillionTree and its alleged affiliates were engaging in review hijacking, bribing customers to turn negative reviews into positive ones, and manipulating Amazon ratings to boost its sales and diminish competitors’ sales.
Moreover, the probative value of Hollenbeck’s opinion outweighs its prejudicial effect because it could help a juror to determine certain facts like whether review hijacking, bribing customers for better reviews, and manipulating ratings constitutes an unlawful, unfair, or fraudulent business act or practice.
3. The Expert Report Applies Reliable Methods
Defendants argued that the Hollenbeck Report should be excluded because it lacked analytical rigor, relied on incomplete data, and failed to account for alternative explanations.
Defendants asserted that, for example, the report did not account for other variables impacting a products’ ranking on Amazon, and that the Hollenbeck Report did not provide evidence supporting its assertion that repurposed reviews misled consumers and caused harm.
Hollenbeck reviewed product pages and analyzed 29 products. He further declared that he performed an analysis of the reviews and product pages downloaded by applying his skills and expertise from marketing academia.
The Court found that his understanding and expertise in the area coupled with the general accepted principle that alternative explanations involve weight, not admissibility, are sufficient to assuage Defendants’ concerns of unreliable methodology.
4. The Expert Report Attempts to Introduce Legal Opinions
Defendants argued that the Hollenbeck Report repeatedly referred to Defendants’ alleged conduct as illegal according to the Federal Trade Commission, which is an impermissible legal opinion.
The Court found that some of Hollenbeck’s opinions constituted improper expert opinions.
In paragraph 9 of his report, Hollenbeck described BillionTree and its alleged affiliates as partaking in review hijacking and opines that “this type of review hijacking is considered illegal by the Federal Trade Commission.” In paragraph 99 of his report, Hollenbeck opined that BillionTree and its alleged affiliates engaged in “harassment and paying for positive reviews which are considered illegal by the Federal Trade Commission.” Interpreting whether conduct constitutes a violation of law regulated by the Federal Trade Commission falls squarely within the Court’s province, as it involves conclusion of law.
Held
The Court granted in part and denied in part the Defendant’s motion to exclude the testimony of Brett Hollenbeck.
Key Takeaway:
Expert witnesses may rely on inadmissible hearsay in forming their opinions, so long as it is of a type reasonably relied upon by experts in their field. Typically, an academic expert in online marketplaces will review comment entries on marketplaces to identify how the products function. In this case, Hollenbeck used the marketplace reviews and applied his expertise to form an independent judgment that BillionTree and its alleged affiliates were engaging in review hijacking.
Case Details:
| Case Caption: | ML Products Inc. V. Billiontree Technology USA, Inc. |
| Docket Number: | 2:23cv8626 |
| Court Name: | United States District Court for the Central District of California |
| Order Date: | August 26, 2025 |
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