United States v. Karo Case Brief

Why is the case important?

The DEA placed a beeper in a can of ether which informant told them was to be used to extract cocaine from clothing imported into the United States. The beeper lead them to a house which the DEA then obtained a warrant to search.

Facts of the case

Defendants James Karo, Richard Horton, and William Harley ordered fifty gallons of ether from a government informant, to be used to extract cocaine from clothes imported into the United States. Carl Muehlenweg, the informant and owner of the ether, gave consent to the police to install a tracking device into one of the cans containing the ether before delivery to the defendants.


Does installation of a beeper in a container of chemicals with the consent of the original owner constitute a search for Fourth Amendment purposes when the container is delivered to a buyer with no knowledge of its presence?
Does monitoring of a beeper fall within the reach of the Fourth Amendment when visual surveillance could not have produced the information produced?


Reverse the decision of the Court of Appeals.
No, transfer of a can containing an unmonitored beeper conveyed no information the recipient wished to keep private, so it conveyed no information at all. It also did not interfere with a possessory interest in a meaningful way so no Fourth Amendment interest was infringed.


Reversing the judgment, the Supreme Court of the United States held that the installation of a beeper in a container of chemicals with the consent of the original owner did not constitute a search or seizure within the meaning of the Fourth Amendment because the transfer did not invade the respondents-defendants’ privacy. According to the Court, the informant’s consent was sufficient to validate the installation. However, the Court noted that the monitoring of a beeper in a private residence, a location not opened to visual surveillance, violated the Fourth Amendment rights of those who have a justifiable interest in the privacy of the residence. The Court concluded that the seized evidence was not subject to suppression because the affidavit information, absent the evidence obtained through the beeper, was sufficient to support probable cause to issue the warrant.

  • Case Brief: 1984
  • Petitioner: United States
  • Respondent: James Karo, et al.
  • Decided by: Burger Court

Citation: 468 US 705 (1984)
Argued: Apr 25, 1984
Decided: Jul 3, 1984