The National Pork Producers Council and the American Farm Bureau Federation are appealing a lower court's decision to throw out their lawsuit seeking to invalidate a 2018 ballot initiative passed by voters barring sales in California of pork, veal and eggs from animals whose confinement failed to meet minimum space requirements.

The pork industry has defended the size of the cages used at pig farms as humane and necessary for animal safety. Animal rights groups have said some pork producers confine mother pigs in cages so small the animals cannot turn around for most of their lives.

The industry groups have argued that the measure, called Proposition 12, violates a provision of the U.S. Constitution known as the Commerce Clause, which gives Congress the power to regulate interstate commerce, by requiring out-of-state producers to comply or face a California sales ban. A legal doctrine called the "dormant" Commerce Clause bars states from passing laws discriminating against commerce in other states.

Proposition 12 violates that doctrine, the pork producers argued in a legal filing, because it would increase costs for pig farmers, nearly all of whom are located outside California. While being the most populous U.S. state and an important market, California produces just 0.1% of the nation's pork.

"If you're looking for an example of an unconstitutional law, this is it," said Michael Formica, chief legal strategist for the pork producers.

Proponents of the law disagree, saying California has the right to set standards for products sold to its consumers regardless of where these are produced.

"There's a long history of state laws that have to do with protecting public health, food safety and animal welfare," said Josh Balk, vice president of farm animal protection at the Humane Society of the United States, which led the campaign to pass Proposition 12 and is a party in the case. "Producers have a choice if they want to sell products within the state's borders that meet that standard."

The San Francisco-based 9th U.S. Circuit Court of Appeals affirmed a district court's decision to throw out the lawsuit, finding no Commerce Clause violation.

President Joe Biden's administration has sided with the pork producers, saying in a Supreme Court brief that states cannot ban products "that pose no threat to public health or safety based on philosophical objections."

'DRAMATIC EXPANSION'

A ruling by the Supreme Court, which has a 6-3 conservative majority, favoring the pork industry would have major implications for Commerce Clause interpretation, according to some legal experts.

The industry is "asking for a dramatic expansion of the doctrine in a way that would call into question all kinds of state laws," lawyer Brian Frazelle of the Constitutional Accountability Center liberal advocacy group, which filed a brief in the case on behalf of law professors, told reporters in a conference call.

Sixteen liberal U.S. senators, including both of California's, had urged Biden's administration to back the law. They wrote that a ruling endorsing the industry's Commerce Clause position "could allow large, multi-state corporations to evade numerous state laws that focus on harms to their constituents, including those addressing wildlife trafficking, climate change, renewable energy, stolen property trafficking and labor abuses."

A group of 20 primarily Republican-governed states led by Indiana said in a brief that upholding Proposition 12 would undermine state sovereignty. Another group of 14 primarily Democratic-governed states and the District of Columbia, led by Illinois, said overturning it would undermine state authority to legislate.

A ruling favoring pork producers could inspire more industry challenges to state regulations, according to Nandan Joshi, an attorney with the consumer advocacy group Public Citizen, which filed a brief supporting California.

Pressed by animal welfare and consumer groups, many food and restaurant companies already have committed to phasing out small confinements for pigs and to buying or producing cage-free eggs.

Proposition 12, passed with the support of about 63% of California voters, set the required space for breeding pigs, or sows, at 24 square feet (2.2 square meters). The current industry standard is between 14 and 20 square feet (1.3 to 1.9 square meters), according to a 2021 report from Dutch banking and financial services company Rabobank.

The measure also increased the space required to house egg-laying hens and calves raised for veal.

Top U.S. pork producer Smithfield Foods, owned by Chinese company WH Group Ltd (0288.HK), said last year it plans to comply with the law. Kansas-based Seaboard Foods, the No. 2 U.S. pork producer, said this year it is was converting some of its production to achieve compliance.