In response to the 9/11 attacks, the U.S. House and Senate passes the Uniting and Strengthening America by Providing Appropriate Tools Required to Intercept and Obstruct Terrorism Act of 2001, or the "Patriot Act."
This bill grants law enforcement agencies greater authority to wiretap suspected terrorists and monitor their Internet activity without a warrant. This includes grassroots movement organizations that they deem as "dangerous" or are perceived as "aiding and abetting terrorists."