Escondido-based Stone Brewing Co. is suing MillerCoors, the beer giant, accusing it of attempting to capitalize on the popularity of the San Diego company’s beers by rebranding MillerCoors’ Keystone line of light beers with an emphasis on the “Stone” in the Keystone name.

A MillerCoors spokesman called the move a publicity stunt, and said beer drinkers have referred to its Keystone line as “Stone” since it launched in 1989.

Stone Brewing, founded by Greg Koch and Steve Wagner in 1996, is the ninth largest craft brewer in the United States.

Conglomerates such as MillerCoors and AB InBev have been snapping up craft brewing companies into their portfolios in recent years in an attempt to capture the innovation happening in the industry segment.

While some San Diego craft breweries have been acquired by mass beer producers, Stone has pledged to remain independent.

“Keystone’s rebranding is no accident,” Dominic Engels, Stone Brewing CEO, said in a dramatic Feb. 12 statement, which included a video of Koch mocking the quality of MillerCoors beers.

The tenor of the announcement from Stone was in line with its irreverent branding. One of its best-known beers, Arrogant Bastard Ale, has the phrase "You're not worthy" on its bottles and cans.

Engels said MillerCoors previously tried to register the Stone trademark and was rejected.

He pointed to the company’s 30-packs, on which the word “Stone” has been prominently displayed since the rebrand, and to its social media team, which Engels said has dropped the “Key” in Keystone in favor of simply “Stone,” as changes that could confuse consumers to MillerCoors' benefit.

“We will not stand for this kind of overtly and aggressively deceptive advertising,” Engels said.

The complaint, filed in U.S. District Court in San Diego, alleges MillerCoors is violating federal and state laws through unfair competition, trademark infringement and other dishonest actions.