[ConservingFreedom]

And it's been used to justify ignoring the Constitution in USSC rulings. (One of Scailia's blurbs justifying the excesses of the War on Drugs is a good illustration thereof — by that particular case's name eludes me at the moment, sorry.)

Are you thinking of this one? (Courtesy of Ken H.)

"Where necessary to make a regulation of interstate commerce effective, Congress may regulate even those intrastate activities that do not themselves substantially affect interstate commerce." --Justice Scalia, concurring in Raich v Gonzales

[OneWingedShark]

"Where necessary to make a regulation of interstate commerce effective, Congress may regulate even those intrastate activities that do not themselves substantially affect interstate commerce." --Justice Scalia, concurring in Raich v Gonzales

No, that's not it; but that's a pretty impressive example of what I mean.
(Thank you for finding it.)