Attaching a GPS device to a person’s vehicle to track their movements constitutes a search within the meaning of the Fourth Amendment. Authorities obtained a search warrant to install a GPS device on defendant’s car as part of a drug trafficking investigation. They did not install the device until after the warrant expired. The device was used to track defendant’s movements for almost a month. When charges were filed against defendant he moved to suppress the GPS evidence as the product of an illegal search. His motion was denied in part. The D.C. Circuit reversed the conviction based on the admission of this evidence. The U.S.S.C. found the government’s use of a GPS monitoring device is a search within the meaning of the Fourth Amendment and therefore must be reasonable. The majority decision was not based on the reasonable expectation of privacy test for challenges to law enforcement surveillance which is generally employed. (Katz v. U.S. (1967) 389 U.S. 347.) The majority based its decision on common law trespass principals, holding that attaching a GPS device to a vehicle (an “effect”) for purposes of data collection constitutes a search because the government physically occupied private property for the purpose of information gathering. The majority stated the reasonable expectation of privacy test “has been added to, not substituted for, the common-law trespassory test.” It affirmed the district court’s reversal. The concurring opinion was critical of the trespass theory, stating the majority should have used the reasonable-expectation-of-privacy test. [Ed. note: Did the high court address the government’s argument regarding a warrant or probable cause standard? See differing opinions in Scotusblog articles: http://www.scotusblog.com/2012/01/jones-confounds-the-press/#more-137791 and http://www.scotusblog.com/?p=137614 ]