(a) GPS evidence emerging in the field of Criminal Justice

In many science and technology products, GPS tracking and positioning device is relatively cheap, small volume, easy to operate, and can be quickly put into to betracking objects (the current judicial practice is the main vehicle). In American, more and more police GPS technology will be applied to the control and the investigation of the crime, a Congressional Research Report shows, law enforcement agencies,federal and state using a wide variety in the criminal investigation of GPS equipment to obtain evidence, and this dependence has caused social and law circles. [3] data show that, only in the state of Virginia Fairfax (Fairfax), the number of police use of GPS evidence in 2005 to 2007 years about the case of 159 [4]. Accordingly, not onlyas a tool for police investigation, more and more criminal cases, GPS evidence has a key role to play, because prosecutors are aware of persuasive GPS evidence to the jury, and have put as substantial evidence in court. [5] murder nanny case after the trial, prosecutors said in the courtroom: Thank God, the car is placed on the GPS tracking device, it provides evidence for the case to a guilty verdict. [6] since 2007, incar GPS evidence for the important dispute cases in large numbers in the federal andstate courts in criminal cases.

(two) the main point of contention GPS admissibility of controversy: search criteria in the emerging technology to track context

1 of current search criteria: a reasonable expectation of privacy

About whether police behavior constitutes the fourth amendment to the Constitutionon the significance of search, the current standard is Katz v. United States caseestablished the "reasonable expectation of privacy". The Federal Supreme Court held that the fourth amendment privacy protection in the Katz case, the object is not place.Judge Harlan described for determining whether the police activities constitutestandard searched the Fourth Amendment: (1) the parties express their actual newsof privacy expectations; and (2) the public think this expectation is reasonable. [7]according to this standard, think the police act constitutes a search to prove two points: (1) the police hope the Court adopted the parties do not want information isknown to the public, (2) the parties want the information protection for private thoughts is reasonable on the objective, which is recognized by the society. Butgenerally speaking, in addition to the exception, the search behavior of the police is tojudge the basis of writ. However, across the gap between theory and practice is noteasy, especially