Last Thursday, the American Civil Liberties Union released documents showing that undercover officers from the Maryland State Police infiltrated and spied on peace and anti-death penalty groups in 2005 and 2006, continuing the surveillance for over a year despite finding no criminal activity. Some of the activists were placed on a watch list under the category "terrorism – anti-war activist."  Leigh Ann Caldwell takes a look at how police infiltration has expanded in the years since September 11th.