Federal law "precludes California's effort ... to impose new rules, beyond any the FSIS has chosen to adopt, on what a slaughterhouse must do with a pig that becomes non-ambulatory during the production process," said Justice Elena Kagan, who wrote the court's unanimous opinion.

The law would have required all downer livestock, including cattle, pigs, sheep and goats, to be euthanized rather than slaughtered. It was passed in the wake of the Westland/Hallmark animal abuse scandal, where undercover video showed downer cattle being beaten by employees.

The National Meat Association, which appealed the law, estimated that 3 percent of pigs sent to slaughterhouses would be considered “downers.” However, veterinarians normally give the animals a few hours to determine if the problem is disease, fatigue, overheating or something else.

“We couldn’t be more pleased that the Supreme Court not only found in favor of our very clear and

reasonable arguments, but that they did so unanimously,” said NMA CEO Barry Carpenter. “We are

also very grateful to attorney Steven Wells, who represented NMA before the Court, and to Assistant

Solicitor General Benjamin Horwich, who represented USDA.”

The Humane Society of the United States, which supported the California law, noted that two New York congressmen introduced legislature last month that would prohibit the slaughter of non-ambulatory animals.

"If the federal government had strong rules and laws on the books, there would be no reason for California or any other state to adopt a reinforcing statute," Humane Society executive director Wayne Pacelle said. "But it's precisely because the Congress and the USDA are in the grip of the meat industry that we have anemic federal laws on the subject."

Sources: AP, NMA