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Smith v. Maryland

Supreme Court of the United States · 1979 · Criminal Procedure

Criminal ProcedureFourth Amendmentthird party doctrinepen registerphone numbersFourth Amendmentsearchpen register

Facts

After a robbery, the victim began receiving threatening and obscene calls from someone claiming to be the robber. Police linked petitioner to a car seen near the victim's home and asked the telephone company to install a pen register at its central offices to record numbers dialed from petitioner's home phone, without first obtaining a warrant or court order. The pen register showed a call from petitioner's phone to the victim's phone, and police then obtained a search warrant for petitioner's residence. Petitioner moved to suppress all fruits of the pen register, arguing that the warrantless installation violated the Fourth Amendment.

Issue

Does the installation and use of a pen register at the telephone company's central offices, at police request and without a warrant, constitute a "search" within the meaning of the Fourth Amendment? More specifically, does a telephone user have a legitimate expectation of privacy in the numbers dialed from his phone?

Rule

The Fourth Amendment applies only when the government invades a person's legitimate expectation of privacy. Under Katz, that inquiry asks whether the individual exhibited an actual subjective expectation of privacy and whether society is prepared to recognize that expectation as reasonable. A person has no legitimate expectation of privacy in information voluntarily conveyed to a third party and exposed to that third party's equipment in the ordinary course of business; accordingly, installation and use of a pen register to record dialed numbers is not a search.

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One of 10 multiple-choice questions for this case. Pick an answer to see why.

In Columbus, Ohio, detectives investigating a series of extortion threats asked Lakefront Telephone Cooperative to attach a device at its switching center to record every number dialed from Noah Brenner's apartment phone for two days. The device did not capture voices, words spoken, whether anyone answered, or whether any call was completed.

Did the police conduct a Fourth Amendment search by using the device without a warrant?

Explanation. Under the majority rule, a pen register that records only numbers dialed is not a search. The key reasoning is that the caller voluntarily conveys the numbers to the telephone company and exposes them to the company's equipment in the ordinary course of business. The device's limited nature matters: it does not acquire the contents of communications, identities of speakers, or whether calls were completed.