The U.S. Supreme Court heard oral arguments Tuesday over a California law that would require breeding pigs be housed with a certain amount of space in order for their pork to be sold in the state.

California voters passed Proposition 12, an animal welfare ballot measure, in 2018. It prohibits the sale of eggs, veal meat and pork meat from animals confined in housing smaller than standards laid out by the state. The state’s law requires breeding pigs to be raised with at least 24 square feet of space in order for their pork, or pork from their immediate offspring, to be sold in the state.

At issue, and at the center of the National Pork Producers Council v. Ross, is whether California’s law violates the Dormant Commerce Clause of the Constitution, which prevents one state from passing legislation that burdens the commerce of other states. The Supreme Court will determine whether the Ninth Circuit Court of Appeals was correct to dismiss the suit or not.

Timothy Bishop, an attorney for the National Pork Producers Council and the American Farm Bureau Federation, said Proposition 12 violates the clause “almost per se."

“It’s an extraterritorial regulation that conditions pork sales on out-of-state farmers adopting California's preferred farming methods for no valid safety reason,” Bishop said.

Bishop said the law burdens interstate commerce, but there is no local benefit to California in return, which he said fails the Pike balancing test. That test says a local law’s burden to interstate commerce can’t outweigh the law’s local benefits.

“No other state makes its farmers house pigs the way that California does,” Bishop said, “and very few farmers do.”

In California’s argument, state Solicitor General Michael Mongan said voters supported Proposition 12 and thus chose to pay higher prices for pork from pigs housed in the way the law requires.

The voters’ local interest, Mongan said, is in “refusing to provide a market to products they viewed as morally objectionable or unsafe.” He said the Dormant Commerce Clause does not stop voters from making that choice.

“Prop 12 is not protectionist or discriminatory,” Mongan said, arguing that it doesn’t control the price of pork in other states. “And it doesn't violate the general principle against regulating wholly extraterritorial commerce. That principle has not been understood to bar states from setting standards for how the goods sold within their borders are manufactured or produced.”

Jennifer Zwagerman, the director of the Drake Agricultural Law Center at Drake University in Des Moines, Iowa, said throughout the oral arguments, the Supreme Court justices were trying to determine “a comfort level” on what is a sufficient basis for one state to impose restrictions that impacts another state.

The justices frequently addressed morality and whether one state could use morals to justify a burden imposed on another state, and drew on various examples to ask questions.

“To me, and in a variety of the questions, it was really trying to find a line that they are willing to draw in this case that they can be comfortable with applying in all sorts of different circumstances, not just this idea of animal welfare,” Zwagerman said.

Justice Amy Coney Barrett questioned the pork industry’s attorneys on the consequences that would unfold if Proposition 12 were ruled to be unconstitutional.

“How many laws would fall? Barrett asked. “California has higher emission standards on automobiles and many other states. Would that fall?”

Bishop, the attorney for the two pork industry groups, said California’s emission standards wouldn’t fall because the state has a waiver from the federal government to regulate emissions.

Justice Samuel Alito asked California’s solicitor general if pork producing states could retaliate against the state with their own food production laws.

“Could a state say ‘We’re really concerned about water shortages so we’re going to prohibit the shipment through our territory or the sale within our borders of any almonds, where the trees are irrigated,'” Alito said. “Could they do that?”

Mongan, California’s solicitor general, said states could do that if it’s focused on the sale within their borders.

“If you adopt a regulation that is just too burdensome to comply with, then the industry will stop serving a state,” Mongan said, “and the state has to decide ‘Do we want a regulation or do we want pork?’”

The Supreme Court also heard from U.S. Deputy Solicitor General Edwin Needler, who sided with the pork producer groups’ argument, and Jeffrey Lamken, an attorney for the Humane Society of the U.S., which sided with California.

California’s law, if upheld, is expected to go into effect in March, six months after California’s Department of Food and Agriculture released its final regulations on Proposition 12.

Massachusetts has a similar law but chose to hold off on implementation until the high court ruled on Proposition 12.

A ruling is expected next year.

“It will have a much broader impact whichever way they end up deciding,” Drake University’s Zwagerman said.

Follow Katie on Twitter: @katiepeikes

This story was produced in partnership with Harvest Public Media, a collaboration of public media newsrooms in the Midwest. It reports on food systems, agriculture and rural issues. Follow Harvest on Twitter: @HarvestPM