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 Florida, an alcohol ignition interlock device (IID) is a measure used to prevent individuals convicted of DUI (driving under the influence) from operating a vehicle while impaired. Florida law mandates the installation of IIDs for all offenders convicted of a second DUI offense. For first-time offenders, the installation of an IID is at the discretion of the court, particularly if the offense involved a minor in the vehicle or the driver had a BAC of 0.15 or higher. The duration for which an IID must be installed varies based on the number of offenses: for a first offense, it may be required for at least six months; for a second offense, at least one year; for a third offense, at least two years; and for four or more offenses, at least five years. The device must be installed by a state-approved technician, and the data collected by the IID, such as breath test results and any attempts to tamper with the device, is reported to the monitoring company and then to the court. The use of IIDs has been shown to significantly reduce the rate of repeat DUI offenses.