United States v. Knotts

United States v. Knotts was a 1983 decision by the United States Supreme Court regarding the use of an electronic surveillance device.

Background
Minnesota law enforcement agents suspected that one of the defendants was purchasing chloroform for the manufacture of illegal drugs, and arranged with the manufacturer to have a radio transmitting beeper placed within the drum of chloroform the next time it was purchased. Following the purchase, the drum was placed into a vehicle driven by another defendant. Police followed the defendants' vehicle after the purchase, maintaining visual contact for most of the journey, however they had to use the beeper to find the cabin where the defendants stopped. The cabin was owned by Knotts, the respondent in this case. Following visual surveillance of his cabin, the authorities acquired a warrant to search the premises, and used the evidence found therein to convict Knotts.

Result
The court ruled that a "person traveling in an automobile on public thoroughfares has no reasonable expectation of privacy in his movements from one place to another.” Such information - the starting point, the stops one made, as well as the final destination, was voluntarily conveyed to anyone. There was no search and seizure and hence no Fourth Amendment violation because this information could be gathered by the public through observation. The police used visual surveillance to gather the majority of this information, just because the final location of the automobile was learned through the use of the beeper and not visually, did not make the surveillance illegal. There was no indication that the beeper was used to gather information from within the private area of Knotts' cabin.