Currently the Executive Branch, particularly the National Security Agency (NSA), has the ability to wiretap Americans international communication without warrants.
This ability to do so stems from not just the USA PATRIOT Act, but also the FISA Amendment Act of 2008.
The manner in which the information is obtained is through dragnet surveillance. Whether a citizen is of interest or not doesn't make a difference because the NSA intercepts 1.7 billion emails, phone calls,texts etc. a day.
This is a great threat to our American Liberties and Rights due to the inability of the Judicial overview, and checks and balances because of things like the "state secrets" privilege excuse to keep this out of court.
For more information visit the ACLU website. (I am NOT petitioning for them)