When Is an Ignition Interlock Device Required After a DUI Arrest?
Drunk driving is a public safety issue, and lawmakers and law enforcement officials use a variety of methods to attempt to address this concern. In recent years, technological approaches have been implemented to help ensure that people who have been arrested or convicted for driving under the influence (DUI) will avoid intoxicated driving. For those who have been arrested for DUI, the question of when an ignition interlock device may be required can be a significant concern.
What Is an Ignition Interlock Device?
An ignition interlock device, often called an IID, is a small piece of equipment installed in a vehicle that measures a driver’s breath alcohol concentration. The device combines a breath-testing unit with a mechanism that controls the vehicle’s ignition system. If the device detects alcohol above a preset limit, it prevents the engine from starting.
How Ignition Interlock Devices Work
Although designs vary among manufacturers, most IIDs include the same basic features. People with these devices installed in their vehicles will need to follow the proper procedures when driving. The devices generally work as follows:
- Initial Breath Sample: Before starting their engine, the driver will blow into a mouthpiece attached to the IID. Some devices may require a driver’s picture to ensure that the person subject to restrictions is the one providing the sample.
- Alcohol Detection: The device will analyze the sample. If alcohol is detected above the programmed threshold, the vehicle will not start.
- Rolling Retests: While the vehicle is in operation, the IID may prompt the driver to provide additional samples at random intervals.
- Data Recording: Test results, attempts to tamper with the device, and any failures will be stored, and they may be transmitted to a monitoring agency or service provider.
Situations Where an IID May Be Required
The circumstances that trigger an IID requirement can vary from state to state. Some states impose broad requirements for many DUI-related offenses, while others use IIDs more selectively. Typical situations where a person may be required to use an IID include:
After a DUI Conviction
Many states require the installation of an IID after a person has been convicted of driving under the influence. The length of time someone must use the device can depend on the factors involved in a case. In many cases, an IID requirement will remain in place for one year or more.
As a Condition for License Reinstatement
If a person’s driver’s license was suspended after a DUI arrest or conviction, an IID may be required before their license can be reinstated. In some cases, a restricted driver’s license or hardship license may allow driving for limited purposes while a suspension is in effect, and the use of an IID may be required to ensure that a person does not drink and drive.
For Repeat DUI Offenses
Many states impose IID requirements on people who have more than one DUI offense. For repeat offenses, the use of an IID may be mandatory, and the required period may be longer than for a first DUI offense.
In Cases Involving High Alcohol Concentration
Some states impose stricter requirements when a driver’s alleged blood alcohol concentration is above a certain level. In these situations, an IID requirement may be added, or the duration for which an IID will be required may be extended.
As an Alternative to a Longer Suspension
In certain jurisdictions, installing an IID can allow a person to regain their driving privileges sooner than would otherwise be allowed. In these cases, an IID may be optional, but it may be the only way to have a driver’s license reinstated early.
Because each state sets its own rules, the exact circumstances in which an IID may be required can differ substantially. A DUI defense attorney familiar with local laws can help explain the specific requirements that may apply in a particular situation.
Frequently Asked Questions About Ignition Interlock Devices
What Happens if Someone Fails an IID Test?
A failed test will prevent a vehicle from starting. The device will record the failure and report it to the appropriate monitoring agency. A failed test may lead to additional consequences, including the extension of the period in which an IID will be required or even the loss of a person’s driving privileges. The specific penalties that will apply will vary by jurisdiction.
Who Pays for the Installation and Maintenance of an IID?
Typically, the person required to use the IID will pay for installation costs, monthly monitoring fees, and routine maintenance. Some states may have assistance programs for people who meet specific financial criteria.
Can an IID Be Installed on Any Vehicle?
Service providers can install IIDs on most passenger vehicles. However, installation may not be possible on certain vehicles due to mechanical limitations or manufacturer restrictions. If a person is subject to IID requirements, they may only drive vehicles equipped with an IID. If a person regularly drives multiple cars, each vehicle may need to have an IID installed.
What Happens When an IID Requests a Rolling Retest While Driving?
The driver is expected to provide a sample as soon as it is safe to do so. The device will provide a window of time in which the test must be taken. Suppose the driver ignores the prompt or the device detects alcohol in their breath above the allowed limit. In that case, the event will be recorded, and the device trigger alerts that will continue until the vehicle is turned off.
Can Someone Circumvent or Tamper With an IID?
IIDs include safeguards that are designed to prevent tampering. Attempts to disable, bypass, or manipulate a device will be recorded and may result in consequences such as extended IID requirements or the loss of driving privileges.
Does an IID Affect the Performance of a Vehicle?
Beyond controlling the ignition system, an IID typically does not affect how a vehicle drives. It may, however, draw a small amount of power, and periodic servicing will usually be required. The driver will typically be required to pay for ongoing maintenance costs.
Addressing Ignition Interlock Devices During a DUI Case
Ignition interlock devices are intended to improve safety by preventing impaired driving. For those who may be facing a driver’s license suspension following an arrest for drunk driving, an IID may allow them to regain their driving privileges more quickly. A DUI defense lawyer can provide guidance for people in these situations, helping them determine the best ways to defend against drunk driving charges and get back on the road as quickly as possible.
Disclaimer: The information provided in this article is for general informational purposes only and should not be construed as legal advice. The content is not intended to offer specific legal guidance regarding DUI offenses or ignition interlock devices. For advice about your particular legal situation, including DUI charges and related matters, please consult with a qualified attorney.




