Posse Comitatus Act and response to Katrina
In the wake of the hurricane, there have been references to the Posse Comitatus Act as barring use of active-duty military in restoring order, and this AP story says lawmakers are considering repealing the Act. If they'd just read the Act, and the Constitution, they'd realize there is no such need.
The Act provides:
"Whoever, except in cases and under circumstances expressly authorized by the Constitution or Act of Congress, willfully uses any part of the Army or the Air Force as a posse comitatus or otherwise to execute the laws shall be fined under this title or imprisoned not more than two years, or both.."
18 USC 1385. Note the exception for uses expressly authorized by the Constitution. When we turn to Article IV, section 4 of that document, we find: "The United States shall guarantee to every state in this union a republican form of government, and shall protect each of them against invasion; and on application of the legislature, or of the executive (when the legislature cannot be convened) against domestic violence."
So the President has, and had, power to use the military to restore order ... provided the Governor requested it.
Likewise there is 10 USC 331: "Whenever there is an insurrections in any State against its government, the President may, upon the request of its legislature or of its governor if the legislature cannot be convened, call into Federal service such of the militia of the other States, in the number requested
by that State, and use such of the armed forces, as he considers necessary to suppress the insurrection."
I suppose we might have to draw a line between insurrection and old-fashioned rape and looting, but at some point the sheer scale of the latter suggests that we're dealing with the former. And there was some shooting by groups at LEOs, which might be considered insurrection on a smaller-than-usual scale.