Opinion of Roberts, C. J.
fairly be characterized as mere costs of compliance but that the panel below seems to have treated as such. Because of Proposition 12’s square footage requirements, farms will be compelled to adopt group housing, which is likely to produce “worse health outcome[s]” and “sprea[d] pathogens and disease.” App. to Pet. for Cert. 229a. Such housing changes will also “upen[d] generations of animal husbandry, training, and knowledge.” Id., at 211a. And “[b]y preventing the use of breeding stalls during the 30 to 40 day period between weaning and confirmation of pregnancy, Proposition 12 puts sows at greater risk of injury and stress during the vulnerable stages of breeding and gestation.” Id., at 223a. These consequential threats to animal welfare and industry practice are difficult to quantify and are not susceptible to categorization as mere costs of compliance.
Writing for a plurality of the Court, Justice Gorsuch relies on this Court’s decision in Exxon Corp. v. Governor of Maryland, 437 U. S. 117 (1978), to conclude that petitioners’ complaint does not plead a substantial burden against interstate commerce. See ante, at 21–25; see also ante, at 3 (opinion of Sotomayor, J.) (also relying on Exxon). In Exxon, petroleum producers sued after Maryland prohibited their sale of retail gas within the State. 437 U. S., at 119. The Court concluded that “interstate commerce is not subjected to an impermissible burden simply because an otherwise valid regulation causes some business[es] to shift from one interstate supplier to another.” Id., at 127. Fair enough. But the complaint before us pleads facts going far beyond the allegations in Exxon. The producers in Exxon operated within Maryland and wished to continue doing so. By contrast, petitioners here allege that Proposition 12 will force compliance on farmers who do not wish to sell into the California market, exacerbate health issues in the national pig population, and undercut established operational practices. In my view, these allegations amount to economic harms against “the interstate market”—not just “particular
