Update, 1/14: Lagunitas has dropped the lawsuit in the wake of negative reactions from around the country. See below for more.

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Yesterday, Petaluma-based Lagunitas Brewing Company, one of the biggest craft brewers in Northern California, filed a trademark infringement complaint against fellow beer giant Sierra Nevada in the U.S. District Court in San Francisco. The suit, over the use of “IPA” in a beer label, may resemble a tempest in a teapot to outsiders, but it has broad implications for the craft brewing industry.

According to the complaint (embedded below), in December 2014, Lagunitas founder Tony Magee became aware that the label on Sierra Nevada’s new Hop Hunter IPA, scheduled to be released January 15, resembled the label on Lagunitas’s flagship IPA, which the brewery first released 20 years ago. From the complaint:

The unique “IPA” lettering used in the Lagunitas “IPA” Family of Trademarks has a distinctive serif font, distinctive kerning (or letter spacing), between the “P” and the “A”, slightly aged or weathered look, with uneven areas on each of the letters, and the elimination of any periods between the letters. These elements together are unique to the iconic design of the Lagunitas IPA.

The similarities are so great, Lagunitas argues, that the new Sierra Nevada beer will either harm Lagunitas’s brand or look like a collaboration. The company is seeking a temporary restraining order against the release of Hop Hunter, as well as financial compensation.

Brendan Palfreyman, a trademark attorney specializing in craft beer, tweeted out news of the suit this morning. He says, “As far as I know, this is one of the first times that two big craft brewers have been in a lawsuit against each other.”

It is a rare sign of discord, he adds, in an industry known for its willingness to work together. Ten years ago, Russian River Brewing Co. and Avery Brewing Co. avoided a similar trademark-infringement lawsuit by jointly producing Collaboration, Not Litigation, basically the beer equivalent of Michael Jackson’s “Beat It” dance-off.

According to Lagunitas founder Tony Magee’s affidavit (also embedded below), Magee says he did reach out to Sierra Nevada CEO Ken Grossman before and after sending a cease-and-desist letter. The Chico brewery, in turn, has just released a statement to the public:

The Complaint alleges that Sierra Nevada’s Hop Hunter IPA design will create confusion among consumers between the Lagunitas IPA and Sierra Nevada’s new Hop Hunter IPA, and we intend to vigorously dispute that any consumer could possibly confuse our Hop Hunter packaging with anything that Lagunitas has.

The lawsuit doesn’t just signify the appearance of discord in a growing yet amicable industry; the differences in the labels are significant enough that any craft brewer using “IPA” in its label may be implicated. Seeing as how IPAs are the most popular style of craft beer in America, quite a few brewers should be concerned.

The Chronicle has reached out to Lagunitas for comment, but has not yet heard back. Below are the full complaint and Tony Magee’s affidavit:

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UPDATE, 1/14: Lagunitas founder Tony Magee posted the following on Twitter, indicating his plan to drop the lawsuit today:

Today, January 13th 2015, has been the worst day ever in 23 years of growing my brewery. Worst. Growing a biz involves defending a biz… — LagunitasT (@lagunitasT) January 14, 2015

Defending a biz requires answers to Hard Questions. Q’s like: Are our Foundations Strong? Are our Flavors right? Are our Labels Defensible? — LagunitasT (@lagunitasT) January 14, 2015

There r many Courts in the world. For me, over the last month, one Court was a series of rebuffed phone calls. Another was a court of law… — LagunitasT (@lagunitasT) January 14, 2015

Today was in the hands of the ultimate court; The Court of Public Opinion and in it I got an answer to my Question; Our IPA’s TM has limits. — LagunitasT (@lagunitasT) January 14, 2015

I don’t know every answer beforehand, so I feel around for the edges and try to learn. Today I was seriously schooled & I heard you well… — LagunitasT (@lagunitasT) January 14, 2015

Tomorrow mornin we’ll Drop the Infringement Suit & get back to answering other Questions. I don’t think I was wrong for wanting to know cuz… — LagunitasT (@lagunitasT) January 14, 2015