In violation of
posse comitatus, active US troops were called out to act as police in the aftermath of a horrific shooting in Alabama. While this can be seen a knee jerk reaction by a community in shock, the fact that the commanders of these military units allowed such actions raise many questions. Special dispensation had to be approved by Congress to allow active troops to be used in the aftermath of the Katrina Hurricane for example.
http://www.examiner.com/x-536-Civil-Liberties-Examiner~y2009m3d17-Did-Army-troops-patrol-the-streets-of-Samson-Alabama