What is an Ignition Interlock Device (IID), and do I need one?

If you have been convicted more than once for driving while intoxicated (DWI), driving with a blood alcohol concentration level (BAC), or driving under the influence of drugs (DUID), you are required to have an IID installed on any vehicle you operate. It must be maintained for six months following the reinstatement date.

An Ignition Interlock Device (IID) is a handheld breath-testing device that is connected to the vehicle’s ignition, horn, and headlights.  To start the vehicle, a driver must breathe into the device without registering a blood alcohol concentration (BAC).

General Requirements

  • Individuals with more than one alcohol offense on their driving record, must have an IID installed prior to:
    • reinstatement of their driving privileges  OR
    • issuance of a Limited Driving Privilege (LDP) or Restricted Driving Privilege (RDP).
  • The IID must be maintained for six months following the reinstatement date, and the driver is required to report to a certified IID vendor (see below) each month for maintenance to ensure the device is working properly.
  • Failure to maintain the device during the six-month period will result in a re-suspension of driving privileges. The applicant will then be required to do the following before driving privileges can be reinstated:
    • have the device serviced / reinstalled (the certified installer will send proof of service or reinstallation to the Driver License Bureau) and
    • pay a $20 reinstatement fee.

NOTE:  In addition to the driver licensing requirements explained above, a court may impose other requirements, such as a period longer than six months.  If a driver is convicted for failing to have an IID installed as required by law, their driving privilege will be revoked for one year.  A second offense requires driving privileges to be revoked for five years.

Device Installers

  • The IID installed must be certified and approved by the Missouri Department of Transportation (MoDOT).  The installer of the device will notify the Department of Revenue after installation has been completed, or upon any failure to maintain the device.
  • For a list of approved ignition interlock devices and installers, contact the Missouri Department of Transportation at 800-800-2358.