I don’t want to get all legal-wonkish here, but Publius notes an interesting comment in Scalia’s dissent in today’s "physician-assisted suicide" case.

Scalia wrote:

From an early time in our national history, the Federal Government has used its enumerated powers, such as its power to regulate interstate commerce, for the purpose of protecting public morality–for example, by banning the interstate shipment of lottery tickets, or the interstate transport of women for immoral purposes. Unless we are to repudiate a long and well-established principle of our jurisprudence, using the federal commerce power to prevent assisted suicide is unquestionably permissible.

Now, in 1999, the Supreme Court majority — including Scalia — held that interstate commerce clause does not empower the federal government to enact a statute criminalizing violence against women (United States v. Morrison).

Will someone ask Scalia to reconcile this?  If, as he says, the federal government can use the Commerce Clause to "protect public morality", then why was the Violence Against Women Act held unconstitutional?

Of course, Scalia’s premise is wrong.  The Commerce Clause does not confer upon the federal government a power to regulate morality.  In fact, this is what the Court said in Morrison:

As we observed in Lopez, modern Commerce Clause jurisprudence has “identified three broad categories of activity that Congress may regulate under its commerce power.” 514 U.S., at 558 (citing Hodel v. Virginia Surface Mining & Reclamation Assn., Inc., 452 U.S. 264, 276—277 (1981); Perez v. United States, 402 U.S. 146, 150 (1971)). “First, Congress may regulate the use of the channels of interstate commerce.” 514 U.S., at 558 (citing Heart of Atlanta Motel, Inc. v. United States, 379 U.S. 241, 256 (1964); United States v. Darby, 312 U.S. 100, 114 (1941)).

Okay.  This means that Congress can regulate things like interstate roads, hotels, shipping lanes, etc.

“Second, Congress is empowered to regulate and protect the instrumentalities of interstate commerce, or persons or things in interstate commerce, even though the threat may come only from intrastate activities.” 514 U.S., at 558 (citing Shreveport Rate Cases, 234 U.S. 342 (1914); Southern R. Co. v. United States, 222 U.S. 20 (1911); Perez, supra, at 150).

This is a little trickier.  This means things like, say, local government ordinances which can impact the entire interstate market.  For example, if Louisiana has a law which discriminates against goods "imported" from another state, Congress can regulate in that area.

“Finally, Congress’ commerce authority includes the power to regulate those activities having a substantial relation to interstate commerce, … i.e., those activities that substantially affect interstate commerce.” 514 U.S., at 558—559 (citing Jones & Laughlin Steel, supra, at 37).

This is the loosy goosy one, because (if you want to get hypertechnical) every tiny piece of human endeavor affects interstate commerce, and it is a judgment call as to whether or not it "substantially affects" it.

Now, where does "morality" come into play on any of these three tiers?  Answer: it doesn’t.  Scalia is just spitballing here.