A Missouri man is seeking to have evidence in his fraud case suppressed, citing an extensive warrantless search conducted by the FBI before the charges were filed. The American Civil Liberties Union recently filed a brief supporting the effort, saying that his rights under the Fourth Amendment were clearly violated when authorities attached a GPS device to his car and left it running 24 hours a day for about two months even though they did not have a warrant to conduct a search.

This Missouri case deals directly with an issue decided late last year by the Supreme Court, in which the justices said that attaching a GPS device to a car should require a warrant.

In cases involving a defendant's Fourth Amendment rights to be free of an unreasonable search and seizure, the issue being contested in the courts is whether or not the evidence that was gathered may be used against that defendant.

Evidence that is gathered illegally should be suppressed under criminal procedure rules and the Federal Rules of Evidence, which both govern the way that an investigation and trial happen. The very specific guidelines are aimed at presenting only a fair and lawfully gathered set of facts to an impartial jury so that they can reach the correct conclusion on the case.

Evidence that is gathered through illegal means such as theft or unlawful surveillance is suppressed as a way to keep the trial process fair and to encourage law enforcement officers to use the right methods to gather evidence.

In this case, the FBI apparently tracked the Missouri man for two full months without obtaining a warrant and then proceeded to charge him with fraud based at least partially on the evidence obtained using the tracking device.

Courts also often suppress evidence that was found lawfully but as the result of some prohibited conduct by police under what is known as the "fruit of the poisonous tree doctrine."

In our next post we'll dig into the specifics of the case and the impact it could have on Missouri residents accused of a crime.

Source: Ars Technica, "ACLU: "reasonable suspicion" not good enough for GPS tracking," Cyrus Farivar, July 17, 2012.