It was a big night for California chickens, cows, and pigs as midterms voters overwhelmingly supported an initiative codifying the most progressive animal welfare protections in the world.

California Proposition 12, which passed with more than 61% of the vote, sets specific space requirements for confined animals raised for food.

Building on a popular but flawed 2008 measure, which was supposed to ensure animals had space to turn around, stretch, and lie down, the updated rules specify square footage for each animal.

The new guidelines are unambiguous and ban sales from producers who don’t comply – even if they are from outside of the state.

The proposition also adds an enforcement mechanism, giving the initiative teeth its predecessor lacked. The state’s department of food and agriculture, alongside its department of public health, will now be charged with overseeing the regulations and violators could face misdemeanor charges and fines.

“California voters have sent a loud and clear message that they reject cruel cage confinement in the meat and egg industries,” Kitty Block, CEO of the Humane Society of the United States, wrote in a statement after the election results were announced.

“Thanks to the dedication of thousands of volunteers and coalition partners who made this victory happen, millions of veal calves, mother pigs and egg-laying hens will never know the misery of being locked in a tiny cage for the duration of their lives.”

The Humane Society was one of several animal rights organizations that backed the ballot, collectively financing more than $13m in support.

They came up against other animal activists from People for the Ethical Treatment of Animals (Peta), the Humane Farming Association and the Friends of Animals, however, who criticized the move for not going far enough.

The Association of California Egg Farmers and the National Pork Producers Council were also in opposition, emphasizing that the new rules would cause food prices to spike.

A campaigner for Prop 12 gathers signatures in California. Photograph: Talia Herman/The Guardian

Beginning in 2020, the law will require that veal sold in the state comes only from calves who have more than 43 sq ft of space, and hens (including chickens, turkeys, ducks, geese and guinea fowl) will have to have at least one sq ft. Two years later, in 2022, the law will expand to include breeding pigs and their babies, banning the sale of pork unless it comes from pigs given at least 24 sq ft of space, and will require all eggs sold to come from “cage-free” hens, defined by the United Egg Producers’ guidelines.

The impact of this initiative is expected to stretch beyond the state, as the new rules affect products sold in California, regardless of where animals were raised. It’s a momentous move poised to create better conditions animals – but it could come at a cost to consumers.

“Everyone agrees farm animals should be treated with care,” the California Farm Bureau Federation president, Jamie Johansson, wrote ahead of the vote. “California egg farmers who have managed to stay in business comply with those rules. All Proposition 12 does is allow trial lawyers to file predatory lawsuits against egg farmers, who provide some of the healthiest food on the planet. Proposition 12 would push egg prices higher in the state that already suffers from the nation’s highest poverty rate.”

Most of the financial focus has been on how this could affect egg producers in an industry that is trying to balance delivering on increasing demand for cage-free eggs, while catering to low-income consumers who rely on cheaper food.

According to a US Department of Agriculture report from 2016, only 10% of the nation’s eggs come from cage-free hens and a shift could cost billions of dollars to the industry. In California’s billion-dollar egg industry, only a third of laying hens are currently uncaged.

According to a fiscal impact report done by the Legislative Analyst’s Office, these expenses are expected to be passed on to purchasers, especially if producers are slow to increase their stock and meet demand for eggs and meat.

Some fear the new law will increase food prices. Photograph: Richard Levine/Corbis via Getty Images

“When a farmer invests in a cage system he’s hoping to get at least a 20-year lifespan,” the National Association of Egg Farmers spokesperson, Ken Klippen, told the Guardian last March. “Then if just a couple years later he’s got to go cage-free, which can cost up to $45 per chicken, the financial burden is so oppressive that some just give up.”

But, while farmers are worried that the regulations will push down production, other opponents said the proposition didn’t go far enough.

“It is a sad day for farm animals and those who care about their mistreatment,” a coalition of animal rights advocate organizations wrote in a statement on the election results.

Calling the statute the “rotten egg initiative”, the group – which included Peta, Friends of Animals (FoA), and was financed by the Humane Farming Action Fund – criticized the timeline that allows for caged hens until 2022.

“Proposition 12 has now rendered the term ‘cage free’ utterly meaningless,” they wrote. “Rather than the full wingspan requirement of our previous law (Prop 2) which is being deleted, hens will now get a mere one square foot of space per bird.”

Still, voters voiced resounding support for the new restrictions, which are currently the most progressive farm animal rights provisions in the world. Big retailers are already on board, and Walmart, Target and Whole Foods have plans in place to sell only cage free by 2025.

“The passage of Proposition 12 is ground-breaking for the welfare of animals and has raised the bar at an important time in our consideration of what farm to table means in this country,” said the Humane Society’s Sara Amundson in a statement. “Californians have resoundingly voted to acknowledge that further expanding the humane treatment of animals matters in our society and we applaud them.”