Prosecutors are not allowed to use evidence in a criminal trial if the evidence was collected illegally, in violation of our Constitutional rights. The Fourth Amendment guarantees us the right to be free from unreasonable search and seizure by the government. This week the U.S. Supreme Court ruled that the prohibition on unreasonable searches included the use of a GPS tracking system that the police had attached to a suspect's car.
The Court said that putting the device on the car constituted a search, and since the police did not have a valid warrant, the information that was obtained using the GPS tracking device could not properly be admitted in the suspect's criminal trial. Therefore the conviction in this suspect's case was reversed.
The most common modern view of the protections of the Fourth Amendment stems from a case in the late 1960's. In that case the police had not entered the suspect's home to obtain information, but instead tapped his phone lines outside of his house. The court determined that this still constituted a search despite the fact that the police never entered his property. Instead the violation of rights occurred when they invaded the suspect's reasonable expectation of privacy.
But the majority in this week's GPS tracking case did not rely upon an invasion into the suspect's reasonable expectation of privacy, instead the majority said that in the act of attaching the device to the car, the police action was tantamount to a trespass. The opinion explained that where there is a trespass for the purpose of obtaining information this constitutes a search.
As more technology related criminal evidence cases come up, it will be interesting to see how this case impacts Fourth Amendment jurisprudence.
Source: Sacramento Bee, "Warrant needed for GPS tracking, high court says," JESSE J. HOLLAND and PETE YOST, Jan. 23, 2012