Feet away from the butchers carving pork loins and beef shanks, the owners of a California meat shop have installed a peculiar sign in their window: “ATTENTION: Animals’ lives are their right. Killing them is violent and unjust, no matter how it’s done.” The odd poster seeming to discourage customers from buying their meats is the result of a months-long dispute between the owners of the Local Butcher Shop – which sells “locally sourced, sustainably raised” meat – and animal rights activists who have staged more than a dozen loud and gruesome protests outside the family-owned business in Berkeley.

With the placement of the sign, written by the activist group Direct Action Everywhere, the vegan protesters have agreed to cease their weekly rallies outside the shop, which sometimes involved nearly nude protesters dripping in fake blood and wrapped in plastic, along with recordings of pigs screaming inside a slaughterhouse.

The 15in-by-15in sign began receiving international attention this week after the activists declared victory, following four months of protests and counter-protests among liberals in the northern California college city widely known for the 1960s free speech movement and anti-war hippies. The anti-meat activists have claimed that the sign is a groundbreaking win and are now promising to target other independent merchants with similar tactics that they hope will spread across the US.

“To be threatened and forced to abide by their beliefs just makes me sad,” said co-owner Monica Rocchino as she sat outside the shop on Wednesday afternoon while customers nearby munched on the sandwich of the day. “Their tactics are really extremist — This is ethical extortion.” Rocchino and her husband, Aaron, opened the shop in 2011, promoting meats in line with a California food culture that values fresh and ethical produce.

Matt Johnson, a Direct Action Everywhere organizer, said that he and his group “challenge places that do put this ‘humane’ marketing out there. People are paying a lot more for these dead animals — They have some notion that these animals are being treated well.”

The group argues that there is no ethical way to kill animals for food and are campaigning to make Berkeley the first “city free of violence toward animals” – meaning banning the sale of meat. The Rocchinos, who partner with local farmers and offer butchery classes, reached out to the activists to find a resolution. Direct Action Everywhere leaders eventually said they would end the protests if the shop agreed to become a “vegan butcher” that did not sell any meat, or if they canceled classes.

Unwilling to sacrifice their entire business, the owners later agreed to a third option: a sign condemning the killing of animals. The activists made two additional concessions: the sign could be three inches smaller than they originally proposed and the shop could place it in a slightly less prominent storefront window. But they said they reserved the right to two protests a year, and that the agreement was “temporary”.

“We want businesses and our culture to face the truth about violence against animals,” said Paul Darwin Picklesimer, an activist who negotiated the agreement, adding: “We do feel that animals are people. We don’t feel that only humans are people, but of course it’s not universally accepted.” The attack on the Berkeley shop and threats of similar protests have sparked backlash across the state.

“I don’t understand why activists would pick on a mom-and-pop shop supporting the most humane farmers, rather than the animal factories and meatpackers responsible for brutality on an unimaginably greater scale,” said Michael Pollan, the well-known American food writer and a University of California, Berkeley professor, in an email. “Unless you believe the complete abolition of meat-eating is a realistic goal, attacking this sector of the animal economy — strikes me as misguided.”

There is a McDonald’s a few blocks away, he added. David Dewey, president of the California Association of Meat Processors, blamed cartoons for making children believe that animals have emotions and feelings. He added: “This is the order of things, even in the wild. Fish eat other fish. Birds eat other birds — That’s just the way the world circles.”

Johnson said the sign was meant to stigmatize meat-eating in the way tobacco warnings discouraged smoking. “Our vision of the world is a world in which every animal has a right to live happy, safe and free as humans by and large do,” he said.

Asked about the rights of humans who aren’t safe and free, such as prisoners, Johnson said: “It’s a form of deflection. It’s a way of not thinking about the issue at hand.”

“I feel like anybody coming here already knows where their meat comes from,” said Ariel Lay, 28, who decided to visit the shop for the first time after reading about the controversy. “They are not going to look at the sign and say, ‘Oh, I had no idea!’” In between bites of her roast beef sandwich, she added, “The whole, ‘We are not going to stop until Berkeley is a vegan city’ thing rubbed me the wrong way. You’re not going to tell me what to eat.”

Richard Healey, a 74-year-old not-for-profit consultant, who works next door to the shop and buys lunch there twice a week, said he suspected people wouldn’t read the poster and that regular customers would continue to be drawn to the delicious meats. “I didn’t even know it was there until someone pointed it out,” he said, adding, “These people make great sandwiches. I think about it and my mouth waters.”