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 Alabama, the use of an alcohol ignition interlock device (IID) is regulated under state law, specifically under the Alabama Code Title 32, Motor Vehicles and Traffic, Chapter 5A, which deals with the Alabama Ignition Interlock Program. The law requires that any person convicted of a DUI offense may be ordered by the court to install an IID on their vehicles. For first-time offenders, the installation of an IID is at the discretion of the court, but it becomes mandatory for repeat offenders. The device must be installed by a certified technician approved by the Alabama Department of Public Safety. The IID prevents the vehicle from starting if the driver's BAC is above the preset limit, typically .02 BAC. The data collected by the IID, including breath test results and any attempts to tamper with the device, is reported to the monitoring company and then to the court. The duration for which an IID must be installed can vary, but it generally ranges from 1 to 3 years, depending on the severity of the offense and the discretion of the court. Despite the effectiveness of IIDs in reducing repeat DUI offenses, compliance rates are not as high as the law intends.