United States v. Karo, 468 U.S. 705 (1984), was a United States Supreme Court

Supreme Court of the United States

The Supreme Court of the United States is the highest court in the United States. It has ultimate appellate jurisdiction over all state and federal courts, and original jurisdiction over a small range of cases...

 decision related to the Fourth Amendment

Fourth Amendment to the United States Constitution

The Fourth Amendment to the United States Constitution is the part of the Bill of Rights which guards against unreasonable searches and seizures, along with requiring any warrant to be judicially sanctioned and supported by probable cause...

 protection from unreasonable search and seizure

Search and seizure

Search and seizure is a legal procedure used in many civil law and common law legal systems whereby police or other authorities and their agents, who suspect that a crime has been committed, do a search of a person's property and confiscate any relevant evidence to the crime.Some countries have...

. It held that use of an electronic beeper device to monitor a can of ether

Ether

Ethers are a class of organic compounds that contain an ether group — an oxygen atom connected to two alkyl or aryl groups — of general formula R–O–R'. A typical example is the solvent and anesthetic diethyl ether, commonly referred to simply as "ether"...

 without a warrant

Warrant (law)

Most often, the term warrant refers to a specific type of authorization; a writ issued by a competent officer, usually a judge or magistrate, which permits an otherwise illegal act that would violate individual rights and affords the person executing the writ protection from damages if the act is...

 constituted an unlawful search. However, the Court upheld the conviction of Karo and his accomplices, stating that the warrant affidavit

Affidavit

An affidavit is a written sworn statement of fact voluntarily made by an affiant or deponent under an oath or affirmation administered by a person authorized to do so by law. Such statement is witnessed as to the authenticity of the affiant's signature by a taker of oaths, such as a notary public...

 contained enough information not derived from the unlawful use of the beeper to provide sufficient basis for probable cause

Probable cause

In United States criminal law, probable cause is the standard by which an officer or agent of the law has the grounds to make an arrest, to conduct a personal or property search, or to obtain a warrant for arrest, etc. when criminal charges are being considered. It is also used to refer to the...

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Background

Drug Enforcement Administration

Drug Enforcement Administration

The Drug Enforcement Administration is a federal law enforcement agency under the United States Department of Justice, tasked with combating drug smuggling and use within the United States...

 agents installed an electronic beeper in a can of ether with the consent of the owner, a government informant. The marked can was sold along with a shipment of 50 gallons of ether to the respondents, who intended to use the ether for the extraction and production of cocaine

Cocaine

Cocaine is a crystalline tropane alkaloid that is obtained from the leaves of the coca plant. The name comes from "coca" in addition to the alkaloid suffix -ine, forming cocaine. It is a stimulant of the central nervous system, an appetite suppressant, and a topical anesthetic...

. Having tracked the can of ether as it was moved between various residences and commercial storage lockers, the federal investigators determined the location of the can and obtained an arrest warrant. Respondent Karo and his accomplices were arrested for possession of cocaine with intent to distribute.

Karo's attorneys petitioned to have various portions of the evidence suppressed

Exclusionary rule

The exclusionary rule is a legal principle in the United States, under constitutional law, which holds that evidence collected or analyzed in violation of the defendant's constitutional rights is sometimes inadmissible for a criminal prosecution in a court of law...

 because they were the "tainted fruit" of an unlawful search. In U.S. v. Knotts, the Court held that the monitoring of a beeper did not violate the 4th Amendment when it revealed no information that could not have been obtained through visual surveillance.

Opinion of the Court

The Supreme Court held that the use of the beeper to conduct surveillance on Karo and his accomplices constituted an unlawful search and seizure in violation of the Fourth Amendment. However, they determined that since the affidavit which led to the issuance of the arrest warrant contained a significant amount of evidence not obtained through use of the beeper (such as the smell of ether emanating from the storage locker and visual tracking of the cans of ether in automobiles), the arrest warrant was valid. Thus, Karo's conviction was upheld.

The majority stated that the installation of the beeper in the can of ether did not constitute "search" or "seizure" by definition. Rather, the Fourth Amendment was not implicated until the beeper was turned on and used to track the ether shipment on private property.