<P> In Exercise Vigilant Shield 2008, Northern Command, Pacific Command, the Department of Homeland Security, and numerous law enforcement agencies across the U.S. conducted exercises to test their "response abilities against a variety of potential threats". </P> <P> The Military Commissions Act of 2006 lifted many restrictions placed on the military to support civilian administration by the Posse Comitatus Act, however the US Supreme Court ruled in June 2008 that significant portions of the MCA were unconstitutional . The "John Warner Defense Authorization Act of 2007" H.R. 5122 (2006) effectively nullified the limits of the Insurrection Act when it was passed; however, the bill was amended in 2008 . </P> <P> On 1 October 2008, the 3rd Infantry Division's 1st Brigade Combat Team was assigned to U.S. Northern Command, marking the first time an active unit had been given a dedicated assignment to Northern Command . The force will be known for the first year as a CBRNE Consequence Management Response Force, and will serve as an on - call federal response force for terrorist attacks and other natural or manmade emergencies and disasters . </P>

The creation of the u.s. northern command was important because