WASHINGTON (AFP) — Justices of the United States Supreme Court seemed baffled by a case that has been brought forth by pork producers seeking to reverse a California law that reduces animal suffering on pig farms after state courts rejected their bid to overturn the measure threatening their business.

Following a grassroots referendum, California passed an animal welfare measure in 2018 that bans the sale of pork from pigs that were raised in overly confined spaces.

The pork industry had gone to court accusing California — which produces little of the pork it consumes — of restricting interstate commerce and trying to impose its values on other states of the country.

The sector fears that California will effectively set national standards for conditions in which farm animals, including cows and chickens, are kept, thus raising ham and bacon prices for consumers.

For nearly two hours on Tuesday, the nine justices pondered the criteria that would allow comparable cases to be resolved in the future.

The result was a series of highly political hypothetical scenarios.

Progressive Justice Elena Kagan wondered what would happen if Democratic states banned the sale of goods made by non-unionized workers.

Her conservative colleague Amy Coney Barrett imagined that they would ban goods from companies that did not fund medical care for their transgender employees.

Judge Brett Kavanaugh, meanwhile, speculated that Republican states might ban products created by undocumented immigrants.

Perplexity peaked when Justice Sonia Sotomayor noted that the pork market was already regulated.

"We have marketed already pork marked as organic, crate-free, antibiotic-free and beta-agonist free," she said. "I have no idea what that means, but I know it's there. I've seen it in supermarkets."

The high court will return a decision before 30 June.