PORTLAND, Ore. – A class action lawsuit was recently filed by approximately 50 craft beer enthusiasts alleging a dozen Oregon breweries have made false claims about the International Bitterness Units (IBUs) in their beers. The names of the breweries have not yet been released.

“Essentially, this is a case of false advertising,” says Tim Crews, one of the plaintiffs filing the suit. “These breweries are putting inaccurate IBU numbers on their beer labels, and it’s time they answered to those misleading claims.”

The IBU is the most popular unit of measurement to describe hop bitterness in beer. IBU calculations are made using a complex mathematical formula that is based on variables such as amounts of hops used, alpha acid percentages in the hops used, the length of time the hops are boiled in the wort, and the volume of wort that is boiled. IBU numbers range from around 10, which is the level you find in many mainstream light lagers, to more than 100, which is what you find in some imperial India pale ales.

“Unless you have a centrifuge and a UV-Vis Spectrometer, you’ll never be able to determine the exact IBU number in a beer.”

There are theoretical limits on just how many IBUs you can infuse, or isomerize, into beer, and there are theoretical thresholds on how many IBUs humans can detect. Most experts agree that both of these upper limits are somewhere around 100, though Mikkel Borg Bjergsø of Mikkeller believes it’s 1,000.

Milford S. Auggenpot, the defense lawyer representing the breweries, admits that the IBU numbers printed on the beer bottle labels may be slightly off, as they are just calculations. But he notes that perceived bitterness is subjective, and he’s quick to point out that a 50-IBU pale ale will seem like it has much more bitterness than a 50-IBU barley wine.

Phil Hague, a member of the American Society of Brewing Chemists, agrees that most IBU numbers out there are just rough estimates, and that most of them are overstated. “Unless you have a centrifuge and a UV-Vis Spectrometer, you’ll never be able to determine the exact IBU number in a beer,” he says. “Of course, you also have to know about isooctanes, isohumulones, hydrochloric acid, flasks and cuvettes, and be nerdy enough to know how to put it all together. Most breweries do not have these things, and they couldn’t afford my salary.”

Complicating matters, the breweries named in the lawsuit chose to use the international hop bitterness scale (IBU) instead of the national hop bitterness scale (NBU), so this has become an international issue, which could delay proceedings. Hop experts from Europe are expected to be subpoenaed.

The lawsuit has also asked the Alcohol and Tobacco Tax and Trade Bureau (TTB), the federal agency that approves beer labels, to investigate the “misleading IBU numbers” on the labels.

“This is a consumer issue that’s just as important as that GMO labeling thing,” says Crews. “I just want to know the correct bitterness level of the beer I’m buying.”