Same ASIN,

different

Product.

9. July 2026

of

Clemens Pfitzer

Can customer reviews on Amazon for an ASIN be reused if the product they refer to has changed? Or is that anti-competitive?

What is it all about?

A company sells balcony solar systems, which are also colloquially referred to as “balcony power plants.” It offered a complete package on Amazon that included solar panels as well as an inverter. A competitor of the company claimed that the package had originally contained an inverter from a specific trademark. The company now ships a unit with an inverter from a different trademark under the same Amazon product identifier (ASIN). According to the platform’s guidelines, such a change would normally require a new ASIN to be assigned. Since this was not done, all customer reviews originally submitted for the package with the previously supplied inverter remained intact and are now incorrectly attributed to the current offering. In response, the competitor issued a cease and desist letter and subsequently filed a motion for a preliminary injunction on the grounds of a violation of competition law .

The company that received the warning contested this. It argued that the assessments presented were merely circumstantial evidence. It could not recall any actual replacement of the inverter. Furthermore, the opposing party would have to explain in more detail how the ASIN had been assigned.

The Cologne Regional Court dismissed the motion for a preliminary injunction. Initially, the court held that a single customer review mentioning a previous inverter was not sufficient to establish a prima facie case. However, after additional relevant reviews were submitted during the proceedings, the Regional Court revised its reasoning. Even assuming that the reviews were misleading, the necessary commercial relevance was lacking, since the reviews in question dated from 2023 and no longer served as an incentive to purchase. Furthermore, consumers were already being accurately informed in the current offer about the inverter actually included at this time.

The competitor filed an appeal against this decision.

Decision of the Higher Regional Court of Cologne

The Cologne Higher Regional Court ruled in favor of the competitor, stating that Decision of May 18, 2026 – Case No. 6 W 30/26 in full. The use of the ASIN for a modified listing is anti-competitive.

The Replacement of the Inverter as Evidence of Misrepresentation

In this case, the Senate found that there was a high probability that the company had replaced the originally installed inverter with a different device but had continued to list the product under the same ASIN. Although the twelve out of approximately 500 customer reviews that explicitly mentioned the old inverter were, taken individually, merely circumstantial evidence, viewed as a whole, this supported the competitor’s claim.

Another decisive factor for the Senate was how the company that received the warning had responded to these allegations. By merely stating that it could not recall any change to the inverter, the company had impermissibly defended itself by claiming lack of knowledge. A company must be informed about the composition of its own products and its own suppliers, especially since it had had sufficient time between the service of the complaint and its response to conduct an internal investigation. Since the relevant information was available only to the company making the offer, it was not the competitor’s responsibility to provide further details regarding the internal procedures involved in assigning the ASIN. Rather, this so-called secondary burden of proof fell on the company against which the claim was made.

Business Relevance of the Rating

The Regional Court had previously denied the commercial relevance of the misleading information, arguing that the twelve relevant reviews were too few to influence consumers. The Senate did not agree with this ruling. The decisive factor was not the number of reviews that explicitly named the earlier inverter, but rather the total number of reviews posted under the continued ASIN for the earlier offer—and thus erroneously attributed to the current product. The total number of reviews is a key criterion for the consumers in question because it allows them to draw conclusions about the product’s popularity and the reliability of the reviews. Double-digit review counts offer no comparable assurance in this regard and are also more susceptible to courtesy reviews.

Practical Tips

Sellers on Amazon should check, when making changes to a listed product, whether this will require them to use a new ASIN for the product, thereby potentially jeopardizing their product’s hard-earned ranking. If an existing ASIN is retained despite such a change, the seller risks receiving cease and desist letters under competition law.

Conclusion

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