California’s Proposition 12, which sets animal-welfare standards for meat sold within the state, has been upheld by the Supreme Court. It’s a ruling that should have been expected, and appellants’ claim that the California law violates the Commerce Clause notwithstanding, the ruling is proper. What a State requires of products sold entirely within it is not interstate commerce—which is the province, and the only aspect that is the province, of the clause.
All Prop 12’s law does is place requirements on the meat sold within the State; it imposes no requirements on how other States comport themselves, including how they raise their food animals. Nothing in the law forces other States to incur the costs of complying with it.