The Supreme Court upheld a California law that bars the sale of pork produced in other states unless the sow was housed in conditions that allowed her to move freely.

The law was the brainchild of animal rights activists in the state, who worked for its passage saying it was necessary to reduce disease from crowded conditions. But the National Pork Producers Council brought a constitutional challenge to the law, arguing that it impermissibly regulates commerce between the states, because nearly all pork production occurs outside of California.

The decision of the court was 5-4, though there was some disagreement among the justices in the majority on the reasons why the California law should be upheld.

"While the Constitution addresses many weighty issues, the type of pork chops California merchants may sell is not on that list," said Justice Neil Gorsuch, writing for the majority.

Chief Justice John Roberts and Justices Samuel Alito, Brett Kavanaugh and Ketanji Brown Jackson dissented from the holding.

At issue is Proposition 12 -- a California law that bans the sale of pork meat, no matter where it is produced, in the state -- unless the pig at issue was born to a sow that was housed with 24 square feet of space and in conditions that allowed her to move freely. Under the law, which has yet to take effect, every sale of covered pork in California that does not meet such standards is considered a crime punishable by a $1,000 fine or a 180-day prison sentence.

The case raised questions regarding not only the issue of animal cruelty but whether one state could regulate another state's production of pork and impose thousands of dollars of charges on pig farmers. While the state said the law was necessary so that Californians wouldn't feel complicit in animal cruelty, pork producers said the law would burden interstate commerce in violation of the Constitution.

"Although the specific issue in this case is very narrow, the implications are quite broad," said Steve Vladeck, CNN Supreme Court analyst and professor at the University of Texas School of Law.

"Today's decision leaves a lot of room for states, by regulating what businesses can and must do within their borders, to impact how those businesses act in other states," Vladeck said. "How far that goes remains to be seen in future cases, but it gives a lot of power, especially to larger states, to influence what happens elsewhere."

The producers told the justices that that the massive costs associated with the law fall almost exclusively on out of state farmers. Across the country 65,000 farmers raise 125 million hogs per year. California accounts for 13% of the country's pork consumption but raises few pigs.

In Thursday's ruling, however, a majority of the justices rejected the arguments that the producers put forward for why the law should be struck down. Gorsuch, writing for the majority, said that the producers were putting forward "aggressive" and "ambitious" interpretations of a legal doctrine known as the dormant Commerce Clause, which is said to forbid state laws that are intentionally discriminatory against interstate commerce.

Gorsuch -- in a part of his opinion joined by Justices Clarence Thomas, Sonia Sotomayor, Elena Kagan and Amy Coney Barrett -- wrote that preventing "state officials from enforcing a democratically adopted state law in the name of the dormant Commerce Clause is a matter of 'extreme delicacy,' something courts should do only 'where the infraction is clear.'"

"Petitioners would have us cast aside caution for boldness," Gorsuch wrote, "They have failed -- repeatedly -- to persuade Congress to use its express Commerce Clause authority to adopt a uniform rule for pork production."

The Humane Society of the United States, a champion of the California law, said Thursday that it was "delighted that the Supreme Court has upheld California Proposition 12 -- the nation's strongest farm animal welfare law -- and made clear that preventing animal cruelty and protecting public health are core functions of our state governments."

Dispute over Constitution's protections for interstate commerce

In court, lawyers for the National Pork Producers -- an organization that says it represents the interests of the $26 billion a year pork industry -- argued that the costs of the law will raise prices across the country and that there is no scientific evidence that the law is necessary to improve sow welfare.

They argued that hardly any commercially-bred sows in the United States are housed in such pens because they are almost universally kept in individual pens during the period between weaning and confirmation of pregnancy for "health and business" reasons. Because of the nature of the industry, a pig is processed into many cuts of meat and sold across the country which would mean that in practical terms, the law regulates the industry across the country, while California imports 99.8% of its pork.

"When a state law is triggered only by in-state sales, a state may not project its legislation into other states" in this way, Timothy S. Bishop, a lawyer for the industry told the justices. "To do so infringes the territorial autonomy of sister states and it impedes our national common market."

The Biden administration sided with pork producers, arguing that the law places a substantial burden on interstate commerce without serving a legitimate local public interest. "It fails to respect the autonomy of California's sister states," Deputy Solicitor General Edwin Kneedler told the justices. "It invites conflict and retaliation and threatens the balkinzation of the national economic union."

But the state argued that the proposition was passed so that the state's citizens would not feel like morally complicit if the pork was produced in a way they regarded as inhumane.

California Solicitor General Michael J. Mongan defended the law telling the court that Prop 12 bars the in-state sale of certain pork products.

"California voters chose to pay higher prices to serve their local interest in refusing to provide a market to products they viewed as morally objectionable and potentially unsafe," he said.

Fractured ruling

The Supreme Court's ruling Thursday showed that the justices were not on the same page about the scope of the Commerce Clause and when it can be used by courts to strike down state regulations because of the way the regulations affect the economic interests of other states.

In a separate part of Gorsuch's opinion, where he was joined only by Barrett and Thomas, he said that courts were not in a position to weigh the costs a state's law may impose on interstate commerce against the benefits the law brings its residents.

"In a functioning democracy, policy choices like these usually belong to the people and their elected representatives," Gorsuch wrote. "They are entitled to weigh the relevant 'political and economic' costs and benefits for themselves ... and 'try novel social and economic experiments' if they wish."

Sotomayor and Kagan, in a concurrence penned by Sotomayor, said they did not join that part of Gorsuch's opinion because they believed courts are capable of weighing those interests. But in this case, they said, the pork producers failed the test. Barrett also wrote separately to say that, while she didn't believe courts could balance those costs and benefits, if courts could, she'd let the lawsuit against the pork regulations go forward.

Roberts -- joined by Alito, Kavanaugh and Jackson -- said he would have sent the case back to lower courts for further consideration on whether the burdens the regulations imposed on interstate commerce outweighed the benefits the pork law brings to California. Kavanaugh wrote an additional concurrence to raise questions he believes the law poses under other clauses of the Constitution.

This story has been updated with additional details.