A federal judge in Seattle has thrown out a class action that used private lab tests to accuse Costco of falsely labeling Kirkland Signature tequila as "100% agave". Hagens Berman brought the case on behalf of 13 buyers under the federal RICO Act and state laws, including Washington's Consumer Protection Act. Costco argued that a U.S. court would intrude on Mexico's exclusive authority to define 100% agave tequila. The judge agreed in an opinion filed Friday, noting that Mexican authorities had already looked at similar claims and rejected them. Plaintiffs' lawyer Steve Berman called the ruling "dead wrong" and said they will appeal.
The background matters. Mexican law lets ordinary tequila draw up to 49% of its alcohol from non-agave sources such as cane sugar or corn syrup. The "100% agave" line on a label is the promise that none of that happened. When a criminal complaint in Mexico in September 2025 raised the same concern, the Tequila Regulatory Council said the products met its standards and that private testing was not proof.
I read this as a ruling about who decides, not a finding that the bottles are clean. That difference matters to anyone building a brand on that label. A U.S. court has deferred to the council, and the council is standing by its own process. For the shopper in the aisle, the label is still the main signal, even after agave farmers protested last year over weak oversight.
This is the gap MezcalSearch was built for: helping drinkers find tequila and mezcal they can trust, with more context than a front label gives them. When premium prices rest on trust, how a spirit is made is part of the product. The producers who keep their pricing will be the ones who show more than the regulator asks for.
For importers and distributors, the lesson is practical. Know your producer and document your supply. The legal question may be settled in Mexico, but the reputational one will be settled by customers.