Unlike with wiretaps, law enforcement agents are not required by federal statutes to obtain search warrants before employing pen registers or trap and trace devices. These devices record non-content information regarding telephone calls and Internet communications. (Of course, "non-content information" has quite a bit of content - who is talking to whom, how often, and for how long.)
The Electronic Privacy Information Center points out in a letter to Senate Judiciary Committee Chairman Patrick Leahy (D-VT) that the Department of Justice has consistently failed to report on the use of pen registers and trap and trace devices as required by law:
The Electronic Communications Privacy Act requires the Attorney General to "annually report to Congress on the number of pen register orders and orders for trap and trace devices applied for by law enforcement agencies of the Department of Justice." However, between 1999 and 2003, the Department of Justice failed to comply with this requirement. Instead, 1999-2003 data was provided to Congress in a single "document dump," which submitted five years of reports in November 2004. In addition, when the 1999-2003 reports were finally provided to Congress, the documents failed to include all of the information that the Pen Register Act requires to be shared with lawmakers. The documents do not detail the offenses for which the pen register and trap and trace orders were obtained, as required by 18 U.S.C. § 3126(2). Furthermore, the documents do not identify the district or branch office of the agencies that submitted the pen register requests, information required by 18 U.S.C. § 3126(8).
EPIC has found no evidence that the Department of Justice provided annual pen register reports to Congress for 2004, 2005, 2006, 2007, or 2008. "This failure would demonstrate ongoing, repeated breaches of the DOJ's statutory obligations to inform the public and the Congress about the use of electronic surveillance authority," they say.
It's a good bet, when government powers are used without oversight, that they will be abused. Kudos to EPIC for pressing this issue. Senator Leahy's Judiciary Committee should ensure that DoJ completes reporting on past years and that it reports regularly, in full, from here forward.