Secret GPS tracking devices, the latest weapon against crime?

(UNDATED) - It's a common technology used to control sex offenders and other criminals, but now more and more law enforcement agencies are secretly using tracking devices as an investigative tool, without a warrant or court order.  Those actions are not sitting well with some citizens.

Police defend the use of GPS devices calling them effective, cost saving technology that essentially is the same as having an officer trail someone.

Opponents disagree, charging GPS devices are an invasion of privacy and violation of the Fourth Amendment and another step toward George Orwell's Big Brother society.

The Washington Post reports how more and more police departments are secretly planting GPS tracking devices on the vehicles of suspected criminals.  A three judge panel of the U.S. Court of Appeals for the 9th Circuit ruled in favor of DEA agents' use of the electronic tracking devices in a case involving a suspected marijuana grower.  The full court declined to rehear the case.

Some analysts predict the trend towards police use of these cheap and effective tracking devices will continue given the courts' support.

What do you think?   Should police be allowed to secretly place GPS devices on your vehicle?  Take our web poll.