Milk, oil, and electricity.

“Imagine if Texas—a state that prides itself on promoting free enterprise—passed a law saying that only those with existing oil wells in the state could drill new wells. It would be hard to believe. It would also raise significant questions under the dormant Commerce Clause. …

Texas recently enacted such a ban on new entrants in a market with a more direct connection to interstate commerce than the drilling of oil wells: the building of transmission lines that are part of multistate electricity
grids. A 2019 law says that the ability to build, own, or operate new lines “that directly [connect] with an existing utility facility . . . may be granted only to the owner of that existing facility.” …

NextEra challenges the new law, as it applies to the interstate electricity networks in Texas (but not the intrastate ERCOT network), on dormant Commerce Clause grounds. … Once we wade through the thicket of electricity regulation, the ban’s interference with interstate commerce becomes as clear as it is for the oil well hypothetical. We thus conclude that the dormant Commerce Clause claims should proceed past the pleading stage.”

NextEra Energy Capital v. Lake, No. 20-50160 (Aug. 30, 2022) (citations omitted).