Click on the following links. Please note these will open in a new window.

PATRIOT Powers Roving Wiretaps
http://www.cato-at-liberty.org/2009/10/15/patriot-powers-roving-wiretaps/

Sneak-and-Peek Warrants
https://www2.fbi.gov/publications/leb/1997/feb975.htm

Emergency Electronic Surveillance
http://www.law.cornell.edu/uscode/50/usc_sec_50_00001805----000-.html