A landmark Supreme Court ruling last month has struck down national law enforcement's efforts to track citizens using GPS technology without properly obtaining search warrants to do so.

The court ruled that GPS tracking devices can only be installed on criminal suspects' vehicles if a warrant has been issued for the criminal investigation. Police in a variety of jurisdictions had been surreptitiously tagging vehicles in an attempt to track the movement of criminal suspects. The justices asserted that tracking without a warrant constituted an illegal search.

The ruling was prompted by a case brought by a Washington, D.C. nightclub owner whose vehicle was tracked for more than a month as part of a drug sting. Police used the information to follow the suspect to a house where money and drugs were stashed and arrested him. The defendant had originally received life in prison for drug crimes before an appeals court overturned the case.

In the criminal case of the nightclub owner, police had obtained a warrant to use a GPS tracking device during their investigation, but police didn't install the equipment until after the warrant had expired. Furthermore, the original warrant was not valid in the jurisdiction where the investigation occurred.

Justices argued that suspects, even those who are aware that they are under investigation, still have a reasonable expectation of privacy. Justices also argued that the implications of GPS tracking extend far past monitoring one's movement related to a criminal investigation. GPS data is extremely intimate, revealing information that is oftentimes irrelevant.

Lawyers for the case say the decision shows the court's commitment to maintaining Americans' Fourth Amendment rights. As technology continues to rapidly evolve, the legal implications and applications of new surveillance equipment used by law enforcement must be continually evaluated.

Source: The Associated Press, "Warrant needed for GPS tracking, high court says," Jesse J. Holland, Jan. 24, 2012