An ignition interlock device (IID) is a breathalyzer built into your vehicle’s ignition system. Before the car will start, you must provide a breath sample below the programmed threshold. Wisconsin law requires IIDs in a growing range of OWI cases.
When Is an IID Required?
Wisconsin requires an IID for:
- All second and subsequent OWI offenses
- First OWI offenses where the BAC was 0.15 or higher
- First OWI offenses with a minor passenger in the vehicle
- OWI offenses involving injury
- Anyone who refused the chemical test
How Long Must You Have It?
The required duration depends on the offense: typically one year for a first offense requiring an IID, longer for subsequent offenses. The IID must be installed on every vehicle you drive — not just the one you drove during the arrest.
Cost and Logistics
You are responsible for the cost of installation, monthly monitoring fees, and removal — typically $70-150 per month total. The device requires periodic calibration appointments. Data from the device is reported to the Wisconsin DMV.
Tampering and Circumvention
Tampering with an IID, driving a vehicle without one when required, or having another person provide a breath sample are all separate criminal offenses that can result in additional charges and extended IID requirements. The devices record all activity, including failed tests and attempts to circumvent.
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Attorney Christopher Carson defends OWI cases throughout Waukesha and Milwaukee counties. Call (262) 860-8932.
About the author. Christopher S. Carson, J.D., M.A., has practiced law in Milwaukee for 34 years. He holds an M.A. in International Security Studies from Georgetown University, where he was the Bradley Fellow, was formerly with the American Enterprise Institute, and is a contributing editor at the New English Review. Read the full biography.
More on this: Criminal defense practice at Carson Law Office · Schedule a free consultation · (262) 860-8932
Related reading: Field Sobriety Tests in Wisconsin: What They Measure and Whether You Can Refuse · OWI vs. PAC in Wisconsin: Why You’re Charged With Two Things at Once · Second-Offense OWI in Wisconsin: When a Ticket Becomes a Crime
This article is general information about Wisconsin law, not legal advice about your situation, and reading it does not create an attorney-client relationship.