In Smith v. Maryland,' the Supreme Court was presented with the question of whether the installation and use of a pen register2 constitutes a "search" under the fourth amendment.3 The pen register is a device which can be used to determine the telephone numbers dialed from a phone under investigation or the number of rings on calls coming into the phone. The question was raised by petitioner Michael Lee Smith, who was convicted of robbery, at least in part, based on evidence obtained from the installation and use of a pen register.4 Smith claimed that the use of a pen register was a search under the fourth amendment and, therefore, the police should have obtained a search warrant prior to its inception.
"The Impact of Smith v. Maryland on the Law of Pen Registers,"
Antioch Law Journal: Vol. 1:
1, Article 15.
Available at: https://digitalcommons.law.udc.edu/antiochlawjournal/vol1/iss1/15