Drinking and driving carries serious legal penalties regardless of the state in question, and for good reason given the dangers. But what happens after a driver is convicted of a DUI can greatly vary depending on the state in which they are found guilty. One such example is state requirements for an interlock ignition device following a DUI conviction.

An ignition interlock device, sometimes referred to as a “car breathalyzer,” is a device for measuring the breath alcohol concentration, or BrAC installed in cars. These systems require the driver to test their BrAC before their vehicle can start. If the driver tests above a predetermined level, the car will not start. Effectively, these systems are a safety measure to prevent an impaired driver from traversing the roads by preventing the possibility of them driving. Many states require those convicted of a DUI, either first or repeat offenders, to install these devices into their cars either during a post-conviction license suspension period or to reinstate their license, according to the Insurance Institute for Highway Safety (IIHS).

States that require drivers to install an IID to reinstate their license following a DUI conviction, regardless if it is their first or repeat offense, include:

• Alaska
• Arizona
• Arkansas
• Connecticut
• Hawaii
• Idaho
• Kansas
• Maryland
• Nebraska
• New Jersey
• New Mexico
• New York*
• North Carolina*
• Oklahoma
• Oregon
• Pennsylvania*
• South Carolina*
• Utah
• Washington
• Wyoming*

In New York, an IID is required to reinstate a driver’s license as condition of “probation or conditional discharge.” In North Carolina, Pennsylvania and Wyoming, an IID is required if the driver’s blood alcohol concentration was above a certain threshold at the time of their arrest. Pennsylvania requires an IID to reinstate a license post-conviction if the offenders’ BAC was above 0.10. In North Carolina and Wyoming that figure is 0.15.

The legal BAC limit in all states except Utah is 0.08.

South Carolina is imposing an IID requirement post-conviction for license reinstatement beginning May 26, 2024.

Far more states, 35, require an IID post-conviction for drivers who are repeat DUI offenders to reinstate their license. These states include:

• Alabama
• Alaska
• Arizona
• Arkansas
• California
• Colorado
• Connecticut
• Florida
• Georgia
• Hawaii
• Idaho
• Illinois
• Iowa
• Kansas
• Maryland
• Massachusetts
• Michigan
• Missouri
• Nebraska
• New Hampshire
• New Jersey
• New Mexico
• New York
• North Carolina
• Oklahoma
• Oregon
• Pennsylvania
• South Carolina
• Texas (if a prior conviction occurred within the last five years)
• Utah
• Vermont
• Virginia
• Washington
• West Virginia
• Wyoming

IID requirements during a post-DUI license suspension period

About half of U.S. states require an IID for a first offender convicted of a DUI to drive during a post-conviction license suspension period. Twenty-one states require drivers to install an IID during a post-DUI-conviction license suspension period to drive regardless of circumstance.

Several other states require an IID during a license suspension period following a DUI conviction under certain circumstances.

Four states — Florida, Michigan, North Carolina and Minnesota — require an IID after a DUI conviction to drive during a license suspension period if the driver’s BAC was above a certain threshold at the time of arrest. In Florida and North Carolina, a driver with a BAC of 0.15 or above at the time of arrest is required to use an IID following conviction. The threshold is 0.16 in Minnesota and 0.17 in Michigan.

Some states, including Idaho and Connecticut, enforce a mandatory license suspension following a DUI conviction. Connecticut imposes a 45-day driver’s license suspension following a DUI conviction. An IID is required afterwards for a driver to reinstate their license.

New York requires a IID during a license suspension period as a condition of probational or conditional discharge following a DUI conviction.

Texas requires an IID following a conviction if a license suspension is imposed. An IID is required for repeat DUI offenders.