We’ve been waiting for this reveal for a while but didn’t expect Costco to enter the fray quite so soon.
Today a Miami-based law firm filed a class action lawsuit accusing Costco of selling adulterated tequila that’s falsely labeled as 100% agave. Rennert Vogel Mandler & Rodriguez are filing on behalf of plaintiff Ariel Glazer. (This is the same law firm that filed a case implicating Kendall Jenner’s 818 tequila in the adulteration scandal on September 23, 2025.)
According to the lawyers, the plaintiff has proof that Kirkland Signature Añejo Cristalino is adulterated with cane sugar–so much so that it can’t be qualified as a mixto. By Mexican law, this means that it is not actually tequila at all. The lawyers go on to build a case that these test results implicate all Kirkland Signature brand tequilas because they are all supposedly made from the same base spirit.
As in the other pending cases, the plaintiff commissioned Nuclear Magnetic Resonance (NMR) testing, which can identify the plant origin of methanol–meaning it can determine if a tequila has been adulterated with corn or cane alcohol. As we previously reported, NMR testing has been approved by the Mexican government as a legitimate method for determining if a tequila is 100% agave. Diageo, the first liquor giant to be slapped with a lawsuit alleging adulterated tequila, has recently called this method of testing into question.
Kirkland Signature (NOM 1173) is a contract brand, currently produced at Newton (Destileria Santa Lucia). It seems extremely challenging to prove that Costco was actually in on the game (although maybe those low prices should have raised their suspicions).
As with the case that implicates 818, this suit sets the date for the statute of limitations based on our reporting and credits the agaveros with first calling attention to this potential issue: “This article covered the prior week’s large-scale, peaceful protest by agave farmers in the historic central square of Tequila, Jalisco, where members of the Mexican Agave Council, and agaveros (agave farmers) from several states convened to make demands on the tequila industry…Only after that public protest and the subsequent coverage by Mezcalistas and other trade publications, could Plaintiff or other Class members reasonably have learned of the adulteration of purported 100% agave tequila with other forms of alcohol. For these reasons, the applicable statutes of limitations for all claims should be tolled until at least January 13, 2025.”
We have reached out to Costco for comment, but have not yet heard back. We will revise this story should we hear from a corporate representative. Stay tuned!
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