It has been just over a year since the U.S. Supreme Court rebuffed a challenge to California’s controversial Proposition 12, which prohibits the sale of certain meat products within the state unless the animals were raised according to certain conditions. Nat'l Pork Producers Council v. Ross, 598 U.S. 356 (2023). Nevertheless, the long-term viability of the law remains unclear, as illustrated by two recent developments: the Supreme Court’s denial of certiorari in Iowa Pork Producers Association v. Bonta, No. 24-728, (U.S., June 30, 2025) and the Department of Justice’s (perhaps unsurprising) decision to file its own challenge to the law in U.S. v. State of California, No. 25-cv-6230 (C.D. Cal., filed July 9, 2025).

Before addressing these developments, it is worth noting that, although the Court upheld Prop. 12 in NPPC, the case was decided without a clear majority opinion. In an opinion joined by Justices Samuel Alito, Brett Kavanaugh and Ketanji Brown Jackson, Chief Justice John Roberts held that the case should have been allowed to move past the pleading stage. He reasoned that, under the facts as alleged, additional factual development might show that Prop. 12, although nondiscriminatory on its face, nevertheless violated the Dormant Commerce Clause by establishing burdens on interstate commerce that clearly outweighed the law’s benefits. Justice Kavanaugh took it a step further, holding not only that further factual development might show Prop. 12 violated the Dormant Commerce Clause, but also hinting that the law might violate other constitutional provisions such as the Import-Export Clause.

The Court might have had an opportunity to clarify things in IPPA, where the petitioners attempted to repackage a similar Dormant Commerce Clause argument. Unlike NPPC, which focused on extraterritoriality and incidental burden, IPPA advanced a theory of intentional discrimination, which the Ninth Circuit rejected. The justices apparently had no appetite to revisit the issue, declining certiorari without comment. Notably, however, Justice Kavanaugh said he would have granted, once again signaling some skepticism about Prop. 12, and perhaps toward attempts by states to dictate economic terms more generally.

Enter the federal government. On July 9, the U.S. Department of Justice filed a lawsuit in the Central District of California that challenges Prop. 12 on the grounds that it is preempted under the Egg Products Inspection Act (EPIA). Only time will tell whether that challenge is viable. The government’s challenge rests on that statute’s express preemption provisions, which limit the ability of states to impose regulations that (i) conflict with federal standards governing egg “quality” and “condition,” or (ii) purport to impose labeling requirements for egg products “in addition to or different from” those required under EPIA or other federal laws. The first position seems like a stretch, given that Prop. 12 does not, at least on its face, seem to impose any standards regarding the quality and condition of the eggs themselves, only the manner in which the eggs are grown. The second may have some legs—Prop. 12’s regulations include a rule regarding use of the term “cage free” that is different from the one used by the USDA.

It is unlikely that the government’s preemption challenge will take down Prop. 12’s egg provisions entirely, but it may limit their reach when it comes to egg products. Regardless, it is all but certain that the government or industry groups will eventually take up Justice Kavanaugh’s invitation to test Prop. 12 on other grounds.

By Associates Robert McClendon and Caitlin Robb

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