"Authority for Use of Military Force to Combat Terrorist Activities Within the United States" is a 37 page classified United States Department of Justice memorandum dated October 23, 2001. This memo states that the President has both constitutional and statutory authority to use the military as a means to combat terrorist activity within the United States. This memo is a direct result of the terrorist attacks on September 11th 2001. Its existence is known because it was referred to in another Department of Justice memo. According to the latter memo, the former memo argued that the Fourth Amendment to the United States Constitution had no application to domestic military operations. The memo has been released to the public.