An ignition interlock device is a type of mini-breathalyzer instrument.  About the size of a cell phone, this car breathalyzer is installed on the steering column of your vehicle. If the judge orders you to install an IID as part of your California DUI probation, you must: have the IID professionally installed, and have an IID installed in every car you own or drive. (Employer-owned cars and motorcycles are exempt from this rule.) Before you start your car, you must blow into the IID and provide an alcohol-free breath sample.  If you don't, your car will not start.  Once you are driving, the IID will ask for random samples, between 5-15 minutes after you begin driving and then about every 45 minutes thereafter. When the instrument asks for these rolling samples, you have six minutes to provide a sample--plenty of time to pull over if you don't feel that you can safely provide a sample while driving. If you don't pass, your ignition interlock device will not disable your car. The IID will, however, register a fail on your log that gets reported to the court.