When you receive a conviction for driving under the influence in California, you may have to install an ignition interlock device on your car once you regain driving privileges. Whether you have to do so depends on several factors.
Per the California Department of Motor Vehicles, the state mandates that you install an IID on your car for somewhere between one and four years if one of two things holds true.
When you must install and use an IID
The state currently requires you to install an IID on any car you drive if you already have one or more DUIs in your driving history and then get another. The state also requires you to do so if the incident that led to your drunk driving arrest resulted in someone getting hurt. There are a few limited exceptions to this. In some cases, the state may require you to get an IID as a first-time offender. In this scenario, you may have to use the device for up to six months.
How the device works
Once you have a provider install the IID in your car and any others you drive, you then have to breathe into it before you start the car and periodically while using it. If the device detects the presence of alcohol on your breath, it prevents the car from starting. It also makes a note of your failed attempt to start it, which may count as a violation.
There are costs involved with installing and maintaining an IID on your car. These costs are your responsibility.