wouldn't need to argue about warrants (of course this does add to the bill). A good lawyer would be get the guy off on the reasonable doubt created by the fact the GPS tracker doesn't prove the defendant was anywhere... The evidence doesn't prove the defendant was with the vehicle.

For those insistent on defeating a tracker, you need to find it first.. to do this you need to know which type is likely to be used:

Passive GPS tracker - this logs the GPS data, which is downloaded later when the device is retrieved. Since they don't emit any RF they are significantly harder to detect. Law enforcement agencies are less likely to use this type (mainly because they are impatient, that and the need to retrieve the device before getting any information).

Remotely activated GPS tracker - these are basically a mobile phone with a GPS receiver. The controller sends a request for the current GPS co-ordinates (the ones I've seen use SMS) which the device then sends back (also via SMS). These are easier to detect (with dirt cheap hardware) but are likely to be ignored by all but the most paranoid.

Realtime GPS tracker - this is an evolution on the Remotely activated GPS trackers. These use 3G internet to provide a (near) realtime GPS feed to a central server These are most likely to be favored by law enforcement (for the realtime aspect if nothing else).

The good new is that if you detect a GPS tracker, they are trivial to defeat:

- remove the power supply

- jam it / wrap it in aluminum foil (why bother when you can just remove the power supply)

- throw it away / leave it in the garage

- attach it to someone else car

- if you're a real geek, take it apart, disassemble the software, find out the server details and the data format being used and have fun spoofing your location (make them think you broke the land speed record... take them on a whirlwind trip around the world).

Mines the one with designs for a garage sized Faraday cage.