Of course, with terrorism as a possibility, the Patriot Act was passed in order to see if it could be headed off. In doing that, though, we have seen a number of rights of American citizens violated. We no longer assume privacy in almost any venue, and are not surprised to know that the government is watching us all the time.
The Patriot Act violates civil liberties by enabling unwarranted wire tapping leading to abuse by authorities, under the pretense of curbing terrorism. Although it's unknown how far reaching the abuse really goes, information concerning the unconstitutional violation of civil rights by the NSA, DEA and other security administrations is constantly being revealed by the media.