DIAGEO Lawsuit: The Chemical Perspective You Didn't Read Yet
A David and Goliath Battle—Or Just Another Marketing War?
What’s This About?
A class-action lawsuit is challenging whether Don Julio Blanco and Casamigos—the two global bestsellers owned by Diageo—are truly 100% agave.
The plaintiffs are seeking over $5 million in damages—but if the case escalates or turns into a broader class action, the financial exposure could grow significantly.
Source: Food and Wine
The Accusation?
That allegedly, a lab test shows a carbon signature more typical of C4 plants (like sugarcane)—rather than agave.
The full test results have not been made public.
Why does this matter? Ethanol derived from C4 plants has a different isotopic fingerprint than agave, which is a CAM plant.
CAM plants, like agave, absorb carbon dioxide at night and store it for photosynthesis during the day—leaving a distinct chemical footprint.
That fingerprint is based on the ratio between carbon-13 and carbon-12 isotopes—an indicator of which plant family the alcohol came from.
But here's the Catch:
The test doesn’t literally say “this came from sugarcane” or “this came from corn.” It says: the ethanol in this sample has a carbon isotope ratio that is not typical of agave, and more typical of plants like sugarcane or corn.
This could suggest adulteration.
Or it could point to something else entirely: legally permitted additives (like caramel or glycerin made from C4 plants), environmental influences on agave, or even testing inconsistencies.
"Something else entirely" means that if the product includes legal additives made from sugarcane (C4), those could shift the isotope ratio even if the ethanol itself is 100% agave. In other words, the test might be picking up the chemical fingerprint of an additive—not the core spirit.
But since additive use in these specific products is not publicly confirmed, we have no way of knowing. And because the full lab methodology has not been released, we don’t know whether additives were removed before testing, how the samples were handled, or how representative they were.
So there is no way to certify the veracity of the test so far.
Diageo Responds
In a statement to Diageo stated:
“The claims are meritless, and we plan to vigorously defend ourselves in court.”
— Diageo, as quoted by Food and Wine
🎯 Possible Motives
“Possible motives from plaintiffs could include consumer protection OR leverage in a competitive space.
From Diageo's side, the case could be seen as a reputational attack or a strategic move against a category leader.”
📊 Market Size
“Diageo controls an estimated 30–35% of the U.S. tequila market, and around 25% of global market value, according to IWSR.
Who’s Involved?
Plaintiffs: Avi Pusateri (mixologist), Chaim Mishulovin (restaurateur), and Sushi Tokyo Inc. (NY restaurant group), represented by Hagens Berman Sobol Shapiro LLP, known for major consumer protection and antitrust cases.
Defendant: Diageo, the world’s largest spirits company, which owns both Casamigos and Don Julio.
Diageo dominates through brands like Don Julio and Casamigos, particularly in the high-end segments.
From Diageo's side, the case could be seen as a reputational attack or a strategic move against a category leader.
What Is Isotope Testing?
The method used is carbon isotope ratio analysis (CIRA)—a forensic test measuring the ratio of two stable carbon isotopes: carbon-13 (13C) and carbon-12 (12C).
Why does this matter? Different plants absorb carbon differently depending on how they photosynthesize:
C3 plants (e.g., grapes, wheat): δ13C = −24‰ to −30‰
C4 plants (e.g., sugarcane, corn): δ13C = −10‰ to −16‰
CAM plants (e.g., agave): typically δ13C = −12‰ to −20‰
So if a spirit’s ethanol shows a strong C4 signature, it raises questions—especially if it's labeled "100% agave."
What does that mean in plain terms?
Think of it like this: different plants leave behind different chemical footprints. If you’re promised tequila made only from agave—but the footprint looks more like sugarcane or corn—that could be a red flag. Or it could be a false signal caused by additives or other ingredients. The test doesn’t say where the carbon came from—it just detects the pattern.
However, this (non-public) test doesn’t prove intent, origin, or fraud. It just flags chemical inconsistencies.
What Did the Test Claim?
The plaintiffs claim that the tequila samples showed a C4-like carbon profile, suggesting the presence of ethanol not derived from agave.
But here’s the issue: The full lab methodology has not been made public.
That means we don't know:
Whether any additives were removed from the tequila before testing (if any are present—which we don't know).
Whether the samples were sealed, opened, or how they were stored
How many samples were tested, and what margin of error was used
Without those details, the results can’t be independently verified.
Do these tequilas contain additives? We don’t know.
Mexican law allows up to 1% post-distillation additives in "100% agave" tequila—without disclosing them on the label. Diageo has not confirmed whether Don Julio Blanco or Casamigos contain additives, and legally, they don’t have to.
If such additives are present—and they include C4-derived ingredients like glycerin or caramel—they could skew isotope readings without altering the actual ethanol source.
Here’s a Theory on Additives
Legally allowed additives like caramel coloring, oak extract, or glycerin are often derived from sugarcane. If those are included in the bottle and weren't removed before lab testing, they could distort the carbon isotope ratio.
That would mean the additive, not the ethanol, triggered the C4 result.
It wouldn’t suggest fraud—it would suggest the wrong part of the product was tested.
Until we see the full lab report, this remains a valid possibility.
What Could Happen Next?
If Diageo wins:
It signals that current laws around additives and CIRA results don’t constitute fraud.
Diageo may be seen as vindicated—and this could be interpreted as a commercial shakedown attempt.
If Diageo loses:
It could set a legal precedent that reinforces chemical testing as valid proof of authenticity.
Regulatory agencies may be pressured to tighten labeling rules or testing oversight.
Diageo could face reformulation demands, labeling scrutiny, or damages.
If the case is settled:
The science may remain untested in court.
Diageo could resolve the case without admitting fault—possibly in exchange for revised practices, or quietly updating formulas or transparency.
Other outcomes:
Consumer trust might still shift based on publicity alone, regardless of verdict.
Diageo might voluntarily retest, reformulate, or improve transparency.
Industry-wide responses (e.g. third-party testing, clearer labeling) may follow.
Smaller brands could use this as a marketing wedge against the majors.
What If It Becomes a Class Action?
If the case is certified as a class action, it could escalate significantly. That would allow the plaintiffs to represent a much larger group of consumers—anyone who purchased Casamigos or Don Julio Blanco in the affected states or possibly nationwide.
This changes the stakes.
A single consumer complaint becomes a multi-million dollar case with wider legal and financial exposure.
More discovery could be required from Diageo.
Public scrutiny would increase, including media, regulatory, and industry attention.
Damages could rise sharply if the court agrees that consumers paid a premium for products that were not as advertised.
If The Court Denies Class Certification
The lawsuit may remain small in scope—or get dismissed entirely. But if it moves forward as a class, it becomes not just a tequila story, but a case about consumer trust in spirits labeling across the board.
Final Sip
This lawsuit isn’t just about two brands. It’s about chemistry, regulation, market power—and perception.
Diageo, a global giant with dominant stakes in both the U.S. and global tequila markets, now finds itself cast in the role of Goliath. Whether this is a legitimate scientific concern, a flawed interpretation of complex chemistry, or simply David throwing a stone in a high-stakes commercial war—it’s too early to say.
The truth may lie in the chemistry—or in the print.