A form of secret caller ID, pen registers identify the destination of outgoing phone calls. Together with trap and trace devices, they form a method of electronic surveillance that allows law enforcement access to routing but not content information. Unlike Title III wiretapping, judges do not determine the appropriateness of this monitoring. Instead, government officials certify that this monitoring would produce information relevant to a crime; judges are then required to grant the order.
Pen registers tend to be used more often than other forms of electronic surveillance. In 1996, the U.S. Department of Justice obtained 4,569 orders covering 10,520 people. These numbers vastly underestimate the true use of these devices, as they do not include other federal agencies and state authorizations.
Constitutional Background
The Supreme Court developed its “reasonable expectation of privacy" tests in Katz v. United States (1967). The consequence of the development of this tests was that wiretaps were unconstitutional searches since communication electronically has a reasonable expectation of being private. In Smith v. Maryland (1979), the Court determined that pen registers are not searches since information with regards to outgoing phone numbers is voluntarily being offered to the phone company.
Changes in the USA PATRIOT Act
Pen Register was initially defined in 1984 as part of the Electronic Communications Privacy Act, as “A device which records or decodes electronic or other impulses which identify the numbers dialed or otherwise transmitted on the telephone line to which such device is dedicated.” Meanwhile, the USA PATRIOT Act extended the concept of pen registers to the Internet by allowing law enforcement authorities access to Internet routing information using the same procedure. However, in updating for technology, the Act drastically increased governmental surveillance power.
Internet routing information cannot easily be separated from its content. Unlike telephone calls, where a pen register only relays phone numbers, Internet monitoring necessarily gathers both routing and content information. We then trust law enforcement to only look at what they are authorized to view. Additionally, law enforcement may use its Carnivore system to gather this information. Carnivore gives law enforcement access to all traffic passing through an ISP, not just the communications of the suspect.
The USA PATRIOT Act permits a federal judge to issue a pen register authorization without naming the specific ISP on which it will be served. Our legal tradition, going back to the Fourth Amendment, requires the order list the place of the search. This change essentially gives law enforcement blank warrants. They can apply for an authorization in Washington D.C. and decide to use it on an ISP in Los Angeles. This undermines the effectiveness of judicial regions and makes it much harder for a small ISP to fight an unjust court order.
Both of these actions violate a reasonable interpretation of the Fourth Amendment. While pen registers are important law enforcement tools, we must be wary of allowing their use in new technologies to undermine our freedoms.
Find out more about Pen Registers
CDT article on the dangers of applying pen register statute to the Internet
http://www.cdt.org/security/000404amending.shtml
EPIC Analysis of Pen Registers
http://www.epic.org/privacy/terrorism/ata_analysis.html
Wikipedia Overview of Pen Registers
http://en.wikipedia.org/wiki/Pen_register
ACLU analysis of PATRIOT Act and Pen Registers
http://www.aclu.org/safefree/general/17326res20030403.html
