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 Delaware, an alcohol ignition interlock device (IID) is a mechanism used as a preventive measure for individuals convicted of driving under the influence (DUI). The device requires the driver to provide a breath sample with a blood alcohol concentration (BAC) below a preset limit, typically .02 BAC, before the vehicle can start. Delaware law mandates that IIDs must be installed by a state-approved certified technician. The device records data such as breath test results and attempts to tamper with the system, which is reported to the monitoring company and then to the court. Delaware courts have the authority to require first-time DUI offenders to install an IID as part of their sentence, and it is mandatory for repeat offenders. The duration for which an IID must be installed can range from one to three years or longer, depending on the court's decision. This requirement can be imposed as a condition for bond or probation. Despite the effectiveness of IIDs in reducing repeat DUI offenses, there is a gap in compliance, with only a fraction of those arrested for DUI/DWI having the device installed.