October 2018

An alcohol interlock is a breath-testing unit that a driver must blow into before starting a vehicle. The device disables the ignition if alcohol is detected. All states have laws either requiring interlocks for certain offenders or allowing courts to order interlocks at their discretion.

Interlocks are typically required during or immediately after a license suspension or revocation that follows a conviction for impaired driving.

Twenty-nine states, the District of Columbia and four California counties have some type of interlock requirement for first offenders. Specifically, in 24 states, the District of Columbia and four California counties, all first-time offenders must install interlocks to drive during a post-conviction license suspension. Only 15 states and four California counties require first-time offenders to spend some period of time with an interlock installed on their vehicle before having their license reinstated. In nine states (Florida, Kentucky, Michigan, Minnesota, New Jersey, North Carolina, Pennsylvania, South Carolina and Wyoming), the interlock requirement applies only to first-time offenders with high blood alcohol concentrations (BACs).

Most states have interlock requirements for repeat offenders. Five states (Indiana, Montana, North Dakota, South Dakota and Wisconsin) have no mandatory interlock requirements.

Licenses also may be suspended or revoked prior to conviction, as soon as a driver fails or refuses to take a chemical test. This procedure is known as administrative license suspension (ALS) and is imposed for the first test failure in 40 states and the District of Columbia. Because ALS occurs immediately, it has been found to be more effective than post-conviction sanctions.

In many states, drivers must install an interlock in order to drive during the ALS, while in other states the interlock requirement only applies to post-conviction suspensions. Requirements may vary, depending on whether it is a first offense or the driver has prior impaired driving convictions. In 14 states, an interlock is required for a first-time offender to drive during the ALS. Another seven states (Alabama, Connecticut, Delaware, Kansas, Massachusetts, New Hampshire and Virginia) do not permit first offenders to drive during the ALS. Connecticut, Idaho and Kansas require an interlock to reinstate the license after the ALS.

Interlock required
State to drive during ALS (first offense) to drive during post-conviction license suspension to reinstate license after conviction
first offender repeat offender first offender repeat offender
Alabama no option for driving during suspension yes yes no yes
Alaska yes yes yes yes yes
Arizona no, although interlock use is incentivized1 no yes yes yes
Arkansas yes yes yes no no
California no, although interlock use is incentivized1 (effective 01/01/19) yes, in Alameda, Los Angeles, Sacramento, and Tulare counties yes yes, in Alameda, Los Angeles, Sacramento, and Tulare counties yes, in Alameda, Los Angeles, Sacramento, and Tulare counties
Colorado yes yes yes no yes
Connecticut no option for driving during suspension, which lasts 45 days, after which interlock required to reinstate no option for driving during suspension, which lasts 45 days, after which interlock required to reinstate no option for driving during suspension, which lasts 45 days, after which interlock required to reinstate yes yes
Delaware no option for driving during suspension2 yes yes yes yes
District of Columbia no yes yes no no
Florida no no, unless offenders' BAC at or above 0.15 yes no, unless offenders' BAC at or above 0.15 yes
Georgia no, although interlock use is incentivized3 no yes no yes
Hawaii yes yes yes yes yes
Idaho no, although interlock required to reinstate (effective 01/01/19) no for offenders with BAC below 0.20; no option for driving during suspension for offenders with BAC at or above 0.204 no option for driving during suspension5 yes (effective 01/01/19) yes
Illinois yes no yes no yes
Indiana no no no no no
Iowa yes yes yes no yes
Kansas no option for driving during suspension, which lasts 30 days, after which interlock required to reinstate for offenders with BAC below 0.15, no option for driving during suspension, which lasts 30 days, after which interlock required to reinstate yes yes yes
Kentucky no ALS for first test failure no, unless offenders' BAC at or above 0.15 yes no, unless offenders' BAC at or above 0.15 yes
Louisiana no, although interlock use is incentivized1 yes yes no no
Maine no, although interlock use is incentivized6 no, although interlock use is incentivized6 yes no no
Maryland no, although interlock use is incentivized3 yes, if license suspension imposed yes yes, for "driving under the influence" violations yes
Massachusetts no option for driving during suspension, which lasts 30 days no yes no yes
Michigan no ALS for first test failure no, unless offenders' BAC at or above 0.17 yes no yes
Minnesota no, although interlock use for offenders below 0.16 is incentivized3 and interlock required for offenders with BAC at or above 0.16 no, although interlock use for offenders below 0.16 is incentivized3 and interlock required for offenders with BAC at or above 0.16 yes no no
Mississippi yes yes yes no no
Missouri no, although interlock use is incentivized1 no, although interlock use is incentivized1 yes no yes
Montana no ALS for first test failure no no no no
Nebraska yes yes yes yes yes
Nevada yes7 yes yes yes yes
New Hampshire no option for driving during suspension yes no option for driving during suspension no yes
New Jersey no ALS for first test failure no option for driving during suspension no option for driving during suspension no, unless offenders' BAC at or above 0.15 yes
New Mexico yes yes yes yes yes
New York no ALS for first test failure yes, as a condition of probation or conditional discharge yes yes, as a condition of probation or conditional discharge yes
North Carolina no no, unless offenders' BAC at or above 0.15 no option for driving during suspension no, unless offenders' BAC at or above 0.15 yes
North Dakota no no no no no
Ohio no no, although interlock use is incentivized3 yes no no
Oklahoma yes yes yes no yes
Oregon no yes yes yes yes
Pennsylvania no ALS for first test failure no, unless offenders' BAC at or above 0.10 yes no, unless offenders' BAC at or above 0.10 yes
Rhode Island no ALS for first test failure yes yes no yes
South Carolina no ALS for first test failure no, for offenders with BAC below 0.15; no option for driving during suspension for offenders with BAC at or above 0.15 no option for driving during suspension no, unless offenders' BAC at or above 0.15 yes
South Dakota no ALS for first test failure no no no no
Tennessee no ALS for first test failure yes yes no yes, when prior conviction occurred within the past 5 years
Texas no yes, if license suspension imposed yes no yes, when prior conviction occurred within the past 5 years
Utah no no option for driving during suspension no option for driving during suspension yes yes
Vermont yes yes yes no no
Virginia no option for driving during suspension, which lasts 7 days yes yes no yes
Washington yes yes yes yes yes
West Virginia yes yes yes no yes
Wisconsin no no no no no
Wyoming no no yes no, unless offenders' BAC at or above 0.15 yes

1Arizona, California, Louisiana, and Missouri eliminate the mandatory ("hard") suspension period if offender chooses to install an interlock.

2In Delaware, the license could potentially be restored during suspension once the Office of Highway Safety has established a continuous sobriety monitoring program.

3Georgia, Maryland, Minnesota, and Ohio grant unlimited driving privileges during the suspension period if the offender chooses to install an interlock.

4In Idaho, any offender with a BAC at or above 0.20 and enrolled in a qualifying problem-solving court shall be eligible for restricted noncommercial driving privileges with an interlock for the purpose of getting to and from work, school, or an alcohol treatment program.

5In Idaho, any repeat offender enrolled in a qualifying problem-solving court shall be eligible for restricted noncommercial driving privileges with an interlock for the purpose of getting to and from work, school, or an alcohol treatment program

6Maine significantly reduces the length of the mandatory suspension period if the offender chooses to install an interlock.

7Nevada requires an interlock as part of the administrative licensing action.