What is vg2 immunity?

Answer 1

VG2 Immunity referrers to the ability of a radar detector to keep you from being seen by the VG2 radar detector detector.

The VG2 radar detector detector is used by police agencies in the U.S. and countries (Canada for one) where the use and or possession of a radar detector is illegal. The authorities use the VG2 to detect whether or not you are using a radar detector.

The VG2 detects the electronic emissions of non-stealthed radar detectors allowing law enforcement to pull over offenders, ticket them and (in Canada and some U.S. states) confiscate the detector.

Radar detectors that use Shadow Technology™ are purported to be shielded in such a way that the amount of detectable emissions allowed to escape the detector are not enough to trigger the VG2 radar detector detector thus making them "immune" to the VG2.

It should be noted that in Canada i believe that use and/or possession of a radar detector is considered "conspiracy to speed" and carries a hefty fine and includes the confiscation of the radar detection unit.

Edit: In Canada, there are certain Provinces were radar detectors are illegal. You are allowed to use them in BC, Alberta, and Saskatchewan.