That law is utterly useless. Its only purpose is to lull people into a sense of safety.
US Constitution Art 1, Sec 8 [portions]As you can see, the Constitution explicitly allows for military enforcement of domestic laws.
To provide for calling forth the Militia to execute the Laws of the Union, suppress Insurrections and repel Invasions;
To provide for organizing, arming, and disciplining, the Militia, and for governing such Part of them as may be employed in the Service of the United States, reserving to the States respectively, the Appointment of the Officers, and the Authority of training the Militia according to the discipline prescribed by Congress;
Try reading more from the Constitution before quoting from it.
The Militia, according to the Constitution, consists of all able-bodied males between the ages of 18 and 40. The Militia consists of the PEOPLE, not Federal troops.
The Federal military forces are highly-trained to take orders from the President. A Militia would consist of people from local areas who would be highly unlikely to follow orders to shoot their neighbors if so ordered. I would rather the Militias be mustered than Federal troops be permitted into an area.
There's a lot of talk about law enforcement being overwhelmed, National Guard, etc. These are issues for the States. The Federal government needs to be invited into a State to assist. They should NOT just have to the right to mosey on in whenever they see fit.
There's a lot of saber-rattling from DC. I hope the Governors, esp. those in the South, are paying attention and are unwilling to assent to a Federal takeover. I would fight for my State of Florida if so ordered, but I would NEVER fight for Obama.