It’s a case about the dormant commerce clause and California’s power to prohibit the in-state sale of pork that comes from conditions California deems cruel. But the Supreme Court’s decision last week in National Pork Producers Council v. Ross had multiple invocations of Shelby County v. Holder and its statements on “equal sovereignty.”

From III-B of the opinion, written by Justice Gorsuch, and joined by Justices Thomas, Sotomayor, Kagan, and Barrett:

To resolve disputes about the reach of one State’s power, this Court has long consulted original and historical understandings of the Constitution’s structure and the principles of “sovereignty and comity” it embraces. BMW of North America, Inc. v. Gore, 517 U. S. 559, 572 (1996). This Court has invoked as well a number of the Constitution’s express provisions—including “the Due Process Clause and the Full Faith and Credit Clause.” Phillips Petroleum Co. v. Shutts, 472 U. S. 797, 818 (1985). The antidiscrimination principle found in our dormant Commerce Clause cases may well represent one more effort to mediate competing claims of sovereign authority under our horizontal separation of powers. But none of this means, as petitioners suppose, that any question about the ability of a State to project its power extraterritorially must yield to an “almost per se” rule under the dormant Commerce Clause. This Court has never before claimed so much “ground for judicial supremacy under the banner of the dormant Commerce Clause.” United Haulers Assn., Inc. v. Oneida-Herkimer Solid Waste Management Authority, 550 U. S. 330, 347 (2007). We see no reason to change course now.[n.1]

[n.1:] 1Beyond Baldwin, Brown-Forman, and Healy, petitioners point to Edgar v. MITE Corp., 457 U. S. 624 (1982), as authority for the “almost per se” rule they propose. Invoking the dormant Commerce Clause, a plurality in that case declined to enforce an Illinois securities law that “directly regulate[d] transactions which [took] place . . . wholly outside the State”and involved individuals “having no connection with Illinois.” Id., at 641–643 (emphasis added). Some have questioned whether the state law at issue in Edgar posed a dormant Commerce Clause question as much as one testing the territorial limits of state authority under the Constitution’s horizontal separation of powers. See, e.g., D. Regan, Siamese Essays: (I) CTS Corp. v. Dynamics Corp. of America and Dormant Commerce Clause Doctrine; (II) Extraterritorial State Legislation, 85 Mich.L. Rev. 1865, 1875–1880, 1897–1902 (1987); cf. Shelby County v. Holder, 570 U. S. 529, 535 (2013) (“[A]ll States enjoy equal sovereignty”). But either way, the Edgar plurality opinion does not support the rule petitioners propose. That decision spoke to a law that directly regulated out-of-state transactions by those with no connection to the State. Petitioners do not allege those conditions exist here. To the contrary, they acknowledge that Proposition 12 regulates only products that companies choose to sell “within” California. Cal. Health & Safety Code Ann. §25990(b).

And in Part IV-D of the opinion (joined here only by Justices Thomas and Barrett), Gorsuch takes aim at Chief Justice Roberts’s opinion concurring in part and dissenting in part, invoking Shelby County (perhaps, in part, because Roberts wrote that opinion):

Seeking a way around that problem, the lead dissent stumbles into another. It suggests that the burdens of Proposition 12 are particularly “substantial” because California’s law “carr[ies] implications for producers as far flung as Indiana and North Carolina.” Why is that so? JUSTICE KAVANAUGH’s solo concurrence in part and dissent in part says the quiet part aloud: California’s market is so lucrative that almost any in-state measure will influence how out-of-state profit-maximizing firms choose to operate. But if that makes all the difference, it means voters in States with smaller markets are constitutionally entitled to greater authority to regulate instate sales than voters in States with larger markets. So much for the Constitution’s “fundamental principle of equal sovereignty among the States.” Shelby County v. Holder, 570 U. S. 529, 544 (2013) (internal quotation marks omitted).