Everything You Need to Know About Ignition Interlock Devices (IIDs) in California DUI Cases

If you have been convicted of a DUI in California, you may be required to install an Ignition Interlock Device (IID) in your vehicle. Ignition Interlock Devices, commonly referred to as IIDs, are miniature breathalyzer instruments that are installed in the dashboard of your car. They prevent your car from operating unless you provide an alcohol-free breath sample. IIDs have become increasingly common as a penalty in California DUI cases.

In this comprehensive guide, our team of California DUI attorneys will answer the most frequently asked questions about Ignition Interlock Devices and California DUI law. We understand that facing a DUI charge can be overwhelming, but we're here to help. If you have any additional questions after reading this article, we invite you to contact us at McGinity Law office.

1. What is an Ignition Interlock Device and How Does it Work?

An Ignition Interlock Device is a type of mini-breathalyzer instrument that is about the size of a cell phone. It is installed on the steering column of your vehicle. If a judge orders you to install an IID as part of your California DUI probation, there are two requirements:

  1. You must have the IID professionally installed.
  2. You must 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. While driving, the IID will ask for random samples, usually between 5-15 minutes after you begin driving and then about every 45 minutes thereafter. If you don't "pass" the breath test, your ignition interlock device will not disable your car, but it will register a "fail" on your log, which gets reported to the court.

California IIDs are designed with advanced technology to ensure that only the driver can provide their own breath sample. They achieve this by requiring a specific breath pattern, having a short cord that will not reach passengers or the back seats, requiring random samples even while driving, and making it a crime to ask someone else to fraudulently provide a breath sample.

In addition, California IIDs can detect and record any attempts to tamper with the device, all engine starts and stops, and all breath test results. It is important to note that you must take your IID in for servicing at least every 60 days.

2. When is an IID Required in a California DUI Case?

A judge may order the installation of an Ignition Interlock Device (IID) in the following situations:

  • Repeat DUI convictions
  • DUI causing injury (Vehicle Code 23153 VC)
  • DUI with a suspended license (Vehicle Code 14601 VC)

For first-time DUI offenses, the length of time an IID must be installed is usually six months. However, if you are not convicted of DUI but found liable by the California Department of Motor Vehicles, the mandatory IID installation period is typically four months.

For repeat DUI offenses, California law requires a criminal judge to order the installation of an IID for the following periods:

  • One year following a second DUI conviction
  • Two years following a third DUI conviction
  • Three years following a fourth or subsequent conviction

If you are convicted of a second DUI causing injury, the IID must be installed for two years, and for a third offense, it must be installed for three years. If you are found liable by the DMV but not convicted of DUI, the mandatory IID installation period is usually one year, regardless of whether it's a second or third conviction.

Additionally, if you have one or more convictions for driving on a suspended license (Vehicle Code 14601) based on a DUI conviction, the judge may order the installation of an IID for one to three years, depending on the exact license violation and the number of prior DUI and/or suspended license violations.

If you are a repeat DUI offender and wish to obtain a restricted driver's license, the California DMV will require you to install an IID. A restricted license allows you to drive to/from work, school, or a court-ordered alcohol program while your regular driver's license is suspended or revoked. It is worth noting that judges are usually willing to grant driving privileges anywhere as long as an IID is installed in the vehicle for a predetermined period of time.

If you do not own a vehicle, you can file for an exemption with the DMV. This generally involves submitting a declaration of non-ownership of a vehicle. Keep in mind that driving without an interlock device when required can result in a probation violation and possible jail time.

3. How Much Does an IID Cost in California?

The cost of an Ignition Interlock Device (IID) in California can vary, but on average, it is about $3.00 per day. Some companies may also charge an installation fee of around $75-$100. In addition to these costs, you may be required to pay fees for maintenance and calibration of the IID.

Under California's mandatory IID pilot program law (Vehicle Code 23700 VC), if you cannot afford the full cost of the mandatory IID, you may be eligible to pay only a portion of the costs. The Department of Motor Vehicles (DMV) will charge an administrative service fee of $103.

4. How Do I Find a Court-Approved IID Installer in California?

If a California court orders you to install an Ignition Interlock Device (IID) in your vehicle, you must go to an authorized installer to have it done. Several private companies are approved by the courts to install IIDs. Some IID installation companies you may want to consider include:

  • Smart Start https://www.smartstartinc.com/
  • Intoxalock https://www.intoxalock.com/
  • LifeSafer https://www.lifesafer.com/
  • Draeger Interlock https://www.draegerinterlock.com/

Make sure to contact the court or your attorney for specific instructions on approved IID installers in your area.

5. Can an IID Register a "False Positive"?

Most Ignition Interlock Devices (IIDs) operate on fuel cell technology, which is alcohol-specific and not affected by outside interference such as cigarette smoke, perfume, or gasoline. This means there is little chance of the IID registering a "false positive" due to these factors.

However, it is important to note that any amount of alcohol blown into an IID will register. This means that if you use mouthwash with alcohol, consume liquor-filled candy, or even eat a pastry that produces low levels of alcohol, the IID will pick up and register alcohol in your breath sample.

The good news is that when alcohol registers, you will usually be given the opportunity to retest almost immediately. The low levels of alcohol present in these situations quickly disappear. Rinsing your mouth with water between breath samples can help expedite this process.


Facing a DUI charge in California can be a daunting experience, but understanding the requirements and processes surrounding Ignition Interlock Devices (IIDs) can help you navigate through the legal system. IIDs are becoming increasingly common as a penalty for DUI convictions, and it is crucial to comply with any court orders regarding their installation. If you have any questions or need legal assistance, our team of California DUI attorneys at McGinity Law office is here to help. Contact us today for a free consultation.

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