Reading through transcripts of oral arguments today, I was struck by the above exchange between Justice Scalia and Solicitor General Verrilli because it completely contradicts something Justice Scalia wrote in one of his most famous opinions.

The contradiction bears on the central issue in the health care case.

In 2005, Justice Scalia issued a concurring opinion in the landmark case Gonzales v. Raich, 545 U.S. 1 (2005), which upheld the federal government’s right to punish people for growing marijuana for their own personal use. Scalia’s concurring opinion was significant because it outlined his view of the scope of Congress’s constitutional authority to regulate commerce. (The authority under the constitution to regulate interstate commerce is the government’s justification for the Controlled Substances Act, which criminalizes the cultivation, use and distribution of marijuana.) The scope of that authority had to be really, really broad to reach some dude who’s growing weed in his back yard for his own personal use, and Scalia made it really, really broad.

Here’s what Scalia said the government could regulate in his Raich concurrence:

1. “the channels of interstate commerce”

2. “the instrumentalities of interstate commerce, and persons or things in interstate commerce”

3. “activities that ‘substantially affect’ interstate commerce” and

4. “where necessary to make a regulation of interstate commerce effective, […] even those activities that do not themselves substantially affect interstate commerce.”

Items 1 and 2 on this list are straightforward enough, Scalia explains, they are the constitutive parts of commerce. Items 3 and 4 (which are crucial to reach the guy who’s growing his own reefer) are not commerce. In Scalia’s words :

“unlike the channels, instrumentalities, and agents of interstate commerce, activities that substantially affect interstate commerce are not themselves part of interstate commerce, and thus the power to regulate them cannot come from the Commerce Clause alone. Rather, as this Court has acknowledged since at least United States v. Coombs, 12 Pet. 72 (1838), Congress’s regulatory authority over intrastate activities that are not themselves part of interstate commerce (including activities that have a substantial effect on interstate commerce) derives from the Necessary and Proper Clause.”

In another place in the concurrence, he writes virtually the same thing in different words:

“The commerce power permits Congress not only to devise rules for the governance of commerce between States but also to facilitate interstate commerce by eliminating potential obstructions, and to restrict it by eliminating potential stimulants. See NLRB v. Jones & Laughlin Steel Corp., 301 U.S. 1, 36—37 (1937). That is why the Court has repeatedly sustained congressional legislation on the ground that the regulated activities had a substantial effect on interstate commerce.”

So, two things to note that Scalia says here:

1. Activities that substantially affect interstate commerce are not, themselves, commerce.

2. A 1937 labor relations case, NLRB v. Jones & Laughlin Steel Corp., permits the regulation of activities that have a substantial effect on interstate commerce (i.e. not commerce).

Now look back up at Scalia’s exchange with Verrilli today. That 1937 case, Jones & Laughlin, is the very one that Verrilli is referring to. Verrilli uses Jones & Laughlin to try to persuade Scalia that the Supreme Court often extends Commerce Clause authority to new areas that have a substantial effect on interstate commerce (in that case, unions, in this case, health care).

But Scalia shuts him down, saying that “there was no doubt” that “what was being regulated” in Jones & Laughlin “was commerce.” That’s the flip flop.

When Scalia is trying to uphold the federal case against a pothead who grows his own, he sees Jones & Laughlin extending the government’s authority far beyond commerce to everything that substantially affects commerce or is necessary to make Congress’s regulation effective. When Scalia is (presumably) trying to strike down Obama’s health care law, there’s no doubt in his mind that Jones & Laughlin is only about regulating commerce.

Unfortunately, Solicitor General Verrilli doesn’t call him on it.