How well do IIDs work – security and tampering?
November 18th, 2008
At first glance, the IID sounds rather easy to circumvent. If one has to blow into a nozzle to start the car, there appear to be several easy ways around this requirement. Have a friend blow into the IID; inflate a balloon before you drink and attach it to the device; keep some sort of hand pump around to trick the IID.
However, there is a statutory requirement that any IID approved for use in Wisconsin institute rolling retests. That is, five minutes after you have started your car, the IID requires another breath test. Moreover, the IID continues to require retests every 5-30 minutes, obviating any chance that a friend or stranger could assist a drunk driver in getting very far.
As far as mechanical methods of tricking the IID, the current generations of IIDs are too clever for that. Some require the user to hum while breathing into the unit; or the IID is sensitive to the temperature of the air being tested, so that cold air from a pump or balloon will result in an aborted test.
Although, someone with sufficient technical knowledge could remove the IID while still allowing the car to start, this tampering information is instantly recorded in the IID, and will be transmitted to the vendor at the servicing time.
Anecdotal evidence suggests that subversion of the IID mechanism is uncommon. But the more pressing issue is not subverting the device, but avoiding IID use altogether.

