The U.S. Supreme Court has preserved a California law banning the sale of pork in America’s most-populous state from pigs kept in tightly confined spaces.

That rejects an industry challenge claiming that the voter-backed animal welfare measure impermissibly regulates out-of-state farmers.

The measure, approved by voters as a 2018 ballot initiative called Proposition 12, bars sales in California of pork, veal and eggs from animals whose confinement failed to meet certain minimum space requirements.

The law mandates pig confinement spaces large enough to enable the animals to turn around, lie down, stand up and extend their limbs.

Animal rights groups have said some pork producers confine pigs in cages so small that pigs cannot turn around for most of their lives.