California law requires ignition interlock devices for certain DUI offenses. Understanding when an IID is required, how it works, the costs involved, and how long you must have one installed is essential for anyone navigating a DUI case in California.
How an IID Works
An Ignition Interlock Device (IID) is a breathalyzer installed in your vehicle's dashboard that prevents the engine from starting if alcohol is detected on your breath. To start the vehicle, you must blow into the device, and it analyzes your breath sample for alcohol content. If the BAC reading is below the programmed threshold (typically 0.02% to 0.04%), the vehicle will start.
The IID also requires "rolling retests" — random breath samples while you are driving to ensure continued sobriety. If a rolling retest is missed or fails, the device logs the event and may trigger the horn or flashing lights to alert law enforcement. All IID data is recorded and reported to the monitoring authority during monthly calibration visits.
When an IID Is Required in California
Under California's IID pilot program (expanded statewide under Senate Bill 1046), IID requirements depend on the offense. For a first-offense DUI in most counties, an IID is required for 6 months if you wish to obtain a restricted license immediately or is optional if you prefer the employment-restricted license after a 30-day hard suspension. For a second DUI offense within 10 years, an IID is required for 1 year. For a third offense, an IID is required for 2 years. For a fourth or subsequent offense, an IID is required for 3 years.
If you are convicted of DUI in criminal court, the court may also order IID installation as a condition of probation, which runs concurrently with any DMV IID requirement.
Costs and Practical Considerations
IID installation typically costs $70 to $150, with monthly calibration and monitoring fees of $60 to $90. The total cost for a 6-month requirement typically ranges from $500 to $900. Financial assistance may be available for low-income drivers through the DMV's IID indigent program.
Practical considerations include scheduling monthly calibration appointments (which can be time-consuming), ensuring the device is functioning properly in extreme temperatures, and the social stigma of having an IID visible in your vehicle. However, for many drivers, the ability to drive without geographic or time restrictions makes the IID the preferred restricted license option.