The latest entry into the debate over Big Brotherism, civil rights and law enforcement is police use of global positioning system (GPS) devices to track suspects.

A Washington Post story by Ben Hubbard last week told how police in Virginia were faced with an rash of 11 attacks on women over a six-month period. They put a GPS device on the truck of a suspect, tracked his movements and arrested him when they caught him "dragging a woman into a wooded area in Falls Church."

More and more the use of GPS devices to track people is becoming more common among police agencies to "snare thieves, drug dealers, sexual predators and killers …" the Post report noted.

Even bike thieves. That's the case at the University of Wisconsin-Madison, where police began using GPS devices attached to "bait bikes" last spring. As of early August they had arrested 16 bike thieves and charged them with "theft of moveable property," a misdemeanor with a $200 fine, according to news reports.

The big difference between these two illustrations, of course, is that the GPS device in Madison is attached to something that doesn't belong to the thief.

In the Virginia case the GPS was put on a suspect's truck and it was placed there without a warrant. That has some civil libertarians riled up. They argue it is a violation of constitutional rights against unreasonable searches. Police and others maintain it is simply an extension of their traditional investigation tools which include the ability to track someone when they are out in public. Plus, of course, it is so much cheaper than having an officer on stakeout.

Police can indeed follow anyone they want to in public, even on the flimsiest of suspicions. But the reality of GPS tracking - and other new technologies as well - is that they go so much further and are more invasive of a citizen's rights because they not only monitor the citizen's movements, but record it for long periods of time. Supporters of GPS tracking contend the issue was settled in a U.S. Supreme Court ruling that emanated from a case right here in Wisconsin, United States v. Knotts, in 1983. The case involved a Minneapolis man who purchased a barrel of chloroform in which a tracking beeper had been placed by law enforcement authorities before it was purchased. The beeper helped lawmen track the barrel to a cabin in Shell Lake, Wis. Authorities got a warrant and a methamphetamine lab was uncovered.

The use of the beeper was challenged, but the high court held in that case that while the suspect had an expectation of privacy in his cabin, that did not apply to the observation of the car on public highways or the barrel of chloroform stored outside the cabin.

As the court put it, "Nothing in the Fourth Amendment prohibited the police from augmenting their sensory faculties with such enhancement as science and technology afforded them in this case."

Planting a beeper in a barrel of chemicals that can be used in an illegal drug lab seems far distant to us from planting a GPS tracker on the vehicle of a citizen simply because police want to see where he or she goes. The potential for fishing expeditions by law enforcement authorities is vastly enhanced in that scenario and that potential will grow exponentially as new vehicles come off the assembly line sporting GPS devices as a common accessory. Police should not be the arbiters in these cases - they should have to make their case for probable cause to a judge, just as they do for wiretaps.

Sometimes technology outstrips case law. Even our Constitution and its protections were written in an era when such devices and search capabilities were unimaginable. The courts should revisit this debate.