Justice Department's Warrantless Spying Increased 600 Percent in Decade | Threat Level | Wired.com

The Justice Department use of warrantless internet and telephone surveillance methods known as pen register and trap-and-trace has exploded in the last decade, according to government documents the American Civil Liberties obtained via a Freedom of Information Act claim.

Pen registers obtain, in real time, non-content information of outbound telephone and internet communications, such as phone numbers dialed, and the sender and recipient (and sometimes subject line) of an e-mail message. A trap-and-trace acquires the same information, but for inbound communications to a target. No probable-cause warrant is needed to obtain the data. Judges are required to sign off on these orders when the authorities say the information is relevant to an investigation.
 
In 2001, the DoJ issued only 5,683 reported “original orders.” (.pdf) Fast forward to 2011, the latest year for which data is available, the number skyrocketed to 37,616 — a more than sixfold increase. Though these can be used to track e-mail, the vast majority are used to get information on mobile phone users’ phone calls and texts.

Justice Department's Warrantless Spying Increased 600 Percent in Decade | Threat Level | Wired.com