Justice Clarence Thomas, writing for the Court in Chevron USA Inc. v. Plaquemines Parish, said the suit challenging Chevron's wartime crude-oil production in the Delta Duck Club field was "closely connected" to its performance of federal avgas refining duties. Justice Samuel Alito took no part in the decision.

The parish sued Chevron in 2013 under Louisiana's 1978 State and Local Coastal Resources Management Act, alleging that the company's use of earthen pits, canals and vertical drilling rendered its pre-1980 operations "illegally commenced" and therefore outside the Act's exemption. Chevron removed under 28 U.S.C. §1442(a)(1), arguing the suit implicated its wartime avgas work.

Thomas wrote that the phrase "relating to" in the statute "sweeps broadly," quoting Morales v. Trans World Airlines for the proposition that the phrase means "to stand in some relation; to have bearing or concern; to pertain; refer; to bring into association with or connection with." He added that the connection can be "indirect" and need not involve "a strict causal relationship."

At the same time, Thomas said, the phrase is "not 'so broad that it is meaningless,'" quoting his own Rutledge concurrence. The ordinary meaning, he wrote, "requires a connection that is not 'tenuous, remote, or peripheral.'"

Applying that standard, Thomas found that Chevron's challenged production methods — vertical drilling, canals and earthen pits — were tied to its federal duties. Vertical drilling "maximize[d] production" of crude oil, canals saved "time, materials, and manpower," and earthen pits complied with the Petroleum Administration for War's "directive to preserve steel." The PAW, Thomas noted, identified the Delta Duck Club field as a "'Critical Fiel[d] Essential to the War Program'" because it produced a "'preferential'" crude oil for avgas refining.

Thomas rejected the Fifth Circuit's reasoning that Chevron's refining contract did not specify how to acquire crude oil and that the PAW's allocation of crude to refineries severed the link between production and refining. "[P]roducing crude oil relates to refining it into avgas, even if the P.A.W. acted as an intermediary allocating the crude oil to refineries," he wrote.

The Court also rejected Louisiana's argument that the statute required Chevron to have been "acting under" a federal officer when it took the specific challenged actions. That reading, Thomas said, "would leave the 'relating to' requirement with little, if any, independent function."

Justice Ketanji Brown Jackson concurred in the judgment but parted ways with the majority on the meaning of the 2011 amendment that added "or relating to" to the statute. "In my view, the statute demands more," she wrote, arguing that §1442(a)(1) "requires a causal nexus between the targeted conduct and the federal duties."

Jackson wrote that the 2011 change was a "conforming amendment" made to address a separate issue — whether presuit discovery proceedings targeting federal officers were removable — not a substantive loosening of the causal-nexus test established in Willingham v. Morgan. She cited the House Report, which stated that federal officers "must demonstrate a causal connection between the charged conduct and asserted official authority." She agreed Chevron satisfied that test because it "produced crude oil, at least in part, to meet the demands of its federal contracts."

Chief Justice John Roberts and Justices Sonia Sotomayor, Elena Kagan, Neil Gorsuch, Brett Kavanaugh and Amy Coney Barrett joined Thomas's opinion. The judgment of the Fifth Circuit, reported at 103 F.4th 324, was vacated and the case remanded.