In United States v. Jones, 565 U.S. 400 (2012), Justice Antonin Scalia wrote for a unanimous court suppressing evidence obtained when the DEA installed a GPS tracking device on a vehicle in order to surreptitiously monitor a suspect's vehicle's movements.
After arrest the suspect moved to suppress evidence uncovered as a result of the warrantless electronic surveillance. In granting the motion to suppress the court held that the warrantless installation and subsequent electronic monitoring of the vehicle's movements was a search under the Fourth Amendment. Since there was no warrant, the monitoring was an illegal warrantless search, ergo fruits of that illegal search, that is, where the suspect had gone while being electronically observed and any evidence the police subsequently derived from that information, was tainted and therefore had to be suppressed.