The owners of Somerville’s Aeronaut Brewing Co. are going through a nasty breakup.

The company is suing its former chief executive, Benjamin Holmes, alleging that he took proprietary information in advance of his recent departure. Holmes says in court filings that the company pushed him out, and he added in an interview that many of the accusations against him amount to misunderstandings with his co-founders, who were his close friends before they became business partners.

Aeronaut is now run by co-founders Ronn Friedlander and Daniel Rassi, who claim that Holmes used company resources for the benefit of his new venture, FAB Beer. The lawsuit says the company had been phasing Holmes out of his role over the past two years due to differences about his “management style.”


But in an interview, the remaining founders said they had no idea that Holmes had been working on the competing project — and using what they consider to be their trade secrets.

“We learned about this in December, and it was a big surprise to us to see what was going on in the background,” Friedlander said.

Among the allegations in the lawsuit filed this week in US District Court in Boston, they say Holmes downloaded company contact lists, attempted to take control of an Aeronaut social media account, and inappropriately accessed beer recipes. They also say FAB’s packaging is deceptively similar to Aeronaut’s, even using the same UPC symbol on one design.

Holmes, who left Aeronaut at the start of the year but remains a shareholder, denies that he did anything that would harm Aeronaut. He said he still feels a deep connection to the company that he founded with Friedlander and Rassi when the three were roommates working on graduate studies at MIT in 2013.

“Aeronaut is a company that was built by friends,” Holmes said in an interview. “And if there’s no friendship, I don’t see how there’s an Aeronaut. I hope they’re friends with each other.”


Friedlander and Rassi said in a statement that they were also saddened by the outcome.

“We’re disappointed that it’s come to this point, but we have to protect the future of this business that we’ve worked so hard to build,” they said. “We are proud of the time, effort, and resources our team has contributed to get Aeronaut to where it is today. However, we do not tolerate unethical practices and procedures from current or former employees.”

Aeronaut has asked for an injunction preventing Holmes from activities including the sale of any beer made using the company’s intellectual property. Holmes has countered that he wants an injunction ordering Aeronaut to return some of his property and documents. The federal judge overseeing the case has not entered a decision on the requests.

Holmes’s attorneys said in a legal filing that he had begun to address many of the issues cited in the lawsuit before it was filed, and that his previous business arrangement with Aeronaut allowed him to start a new company in the same industry. They said in court documents that the three beer recipes that FAB Beer has released so far have been derived, with permission, from the Dorchester Brewing Company, where FAB Beer is a guest brewer.

The filings in the lawsuit put significant emphasis on the design of FAB Beer’s cans. Can designs are a huge branding factor for craft brewers. In one document, Aeronaut attached a series of social media posts by customers and sellers who believed FAB Beer was an Aeronaut-sanctioned product.


Holmes acknowledges that his new company has employed artists whom he worked with at Aeronaut. But he said the FAB Beer products have a unique theme. They feature protest art, with the first designs using imagery that mocks President Trump.

In the interview, Holmes said he believes the products are distinct enough that drinkers will be able to tell them apart.

He urged customers to buy a four-pack of both brands, and “drink them side by side and see if they can tell the difference — because I sure can.”

Andy Rosen can be reached at andrew.rosen@globe.com.