California’s contentious animal welfare requirements are in effect beginning Monday and could lead to higher prices for consumers across the country following a lengthy and national legal battle that made its way to the Supreme Court last year.

Proposition 12, a 2018 California ballot measure that passed by wide margins, requires farmers to provide more space to allow for “freedom of movement” for veal calves, breeding pigs, and egg-laying hens.

The measure made national headlines and sparked outrage from out-of-state meat producers, because it banned California businesses from selling animal products produced in violation of the requirements. 

Supporters of the proposition, including the Humane Society of the United States, called it the “greatest legal victory in animal protection history.” Opponents, who took the issue to the Supreme Court and lost, said it would unconstitutionally regulate interstate commerce and impose expensive burdens on consumers and farmers across America.

“California is attempting to set the rules for the entire country,” American Farm Bureau Federation’s president, Zippy Duvall, said in a statement. 

 “Almost all of the pork consumed in California is produced outside of its borders,” Mr. Duvall said. “This law has the potential to devastate small family farms across the nation through unnecessary and expensive renovations, and every family will ultimately pay for the law through higher food prices.”

The Supreme Court, in a 5-4 ruling, said that California’s law banned the sale of pork products “derived from breeding pigs con- fined in stalls so small they cannot lie down, stand up, or turn around.” The court said the farmers and pork producers that filed the suit — the American Farm Bureau Federation and the National Pork Producers Council — were arguing the requirements interfered “with their preferred way of doing business.” 

“Companies that choose to sell products in various States must normally comply with the laws of those various States,” the Court’s majority opinion, delivered by Justice Gorsuch, noted, adding that while the Commerce Clause prevents states from discriminating purposefully against out-of-state economic interests, the pork producers were not asserting that Calfironia was doing so. 

The pork producing groups asked the court “to fashion two new and more aggressive constitutional restrictions on the ability of States to regulate goods sold within their borders. We decline that invitation,” the Court ruling noted. “While the Constitution addresses many weighty issues, the type of pork chops California merchants may sell is not on that list.” 

Although groups like the Humane Society have praised the Supreme Court’s upholding of Proposition 12, arguing that it will ensure that pigs, hens, and calves are not “cruelly confined,” other animal activists say California’s new requirements are “meager improvements” that don’t go far enough. “The cycle of forced breeding, imprisonment, and death will continue for all pigs in the pork industry,” a PETA statement noted. “Consumers should also be horrified to know that Prop 12 still allows tens of thousands of hens to be crammed into a single shed and does nothing to prevent routine cruelty.”