From Title 4 § 8(k) of the U.S. Code:

The flag, when it is in such condition that it is no longer a fitting emblem for display, should be destroyed in a dignified way, preferably by burning.

From House Joint Resolution 10, passed by the U.S. House of Representatives this past Wednesday:

The Congress shall have power to prohibit the physical desecration of the flag of the United States.

I’ll just come out and admit it — I don’t understand. (And apparently, neither does John Scalzi, who’s post on cracking the amendment ends with a comment I’d love on a bumper sticker: “Real Americans don’t take away the freedoms of other Americans.”)