An alcohol ignition interlock device (IID) is a breath-test device that is connected to a vehicle’s ignition. A vehicle with an IID installed will not start unless the driver blows into the interlock and has a blood alcohol concentration (BAC) below a limit set by the court—usually .02 BAC. IIDs must be installed by a certified technician approved by the state’s department of motor vehicles (DMV). The IID will collect data (engine starts and stops, breath test results, and tampering attempts) and report it to the monitoring company, which will report it to the court.

IIDs reduce repeat offenses for DUI/DWI by approximately 70% when installed. Laws vary from state to state and courts have significant discretion, but a judge may order a person convicted of a first DUI/DWI offense to install an IID and will order a person convicted of a second or third DUI/DWI to install an IID. Courts will often order an IID installed on the defendant’s vehicle as a condition of bond (to be released from jail) and of probation (following jail or prison time, or in lieu of any or more jail or prison time). The court may order the defendant’s IID to remain on the vehicle for 1-3 years or more.

Despite these laws and programs, only about one-fifth of those arrested for DUI/DWI have an IID installed.

In North Carolina, the use of an alcohol ignition interlock device (IID) is mandated by law for certain driving while impaired (DWI) offenses. North Carolina General Statute § 20-179.3 outlines the requirements for IID installation for drivers convicted of DWI. Specifically, an IID is required for all drivers who are convicted of DWI with a blood alcohol concentration (BAC) of 0.15 or higher, for repeat DWI offenders, and for those who are convicted of DWI while driving with a revoked license due to a prior DWI. The period for which the IID must be installed varies depending on the number of offenses and the specific circumstances of the conviction, but it typically ranges from one year to several years. The device must be installed by a certified technician approved by the North Carolina Division of Motor Vehicles (DMV), and the driver is responsible for the costs associated with the IID, including installation, lease, and maintenance. The IID is designed to prevent the vehicle from starting if the driver's BAC is above the set limit, and it records data for monitoring purposes. Failure to comply with IID requirements can result in further legal consequences, including extended revocation of driving privileges.