How many states require an ignition interlock after a first DUI?
Read strictly from the statutes, 22 jurisdictions make an ignition interlock mandatory for every first DUI conviction, 12 more make it mandatory only above a stated blood-alcohol level, and 17 leave it to the court or attach it to a restricted license. The widely quoted figures of 27, 31 and 34 are not wrong — they count something different.
Four organizations, four numbers
| Source | Count | What is being counted | As of |
|---|---|---|---|
| MADD | 34 states + DC | "require these devices for all convicted drunk drivers" (BAC .08 or greater) | 2025 map |
| NCSL | 31 states + DC | all offenders, including first-time; separate lists for high-BAC + repeat, repeat-only, and discretionary | 2024-03-14 |
| GHSA | 27 states | "mandatory or highly incentivized for all convicted drunk drivers, even first-time offenders" — GHSA notes it defers to state highway-safety offices’ interpretation | 2025-10 |
| WheelsBack | 22 + 12 high-BAC | the statute says the device shall be required for every first offense (required), only above a BAC threshold (high-BAC), or it is discretionary / a restricted-license condition — each state quoted and linked | August 29, 2026 |
Why the counts differ
- “Highly incentivized” is not “mandatory.” In many states a first offender can serve the suspension without a device, but must install one to get a restricted license. MADD and GHSA count those states as all-offender; GHSA says so explicitly. A statute-only reading does not, because the statute does not say shall.
- BAC thresholds. Twelve states mandate a device for a first offense only at or above a stated level, usually 0.15. Some counts fold those into “all offenders”; some keep them separate.
- Dates. Legislatures change these rules every session. NCSL’s list carries a March 2024 date; South Carolina’s all-offender law took effect that May. Any count is a snapshot, which is why every WheelsBack state page shows its verification date and this site re-checks its sources monthly.
State by state: statute reading vs. NCSL (March 2024)
14 of 51 jurisdictions land in a different group depending on the definition. Click a state for the statute text behind our reading.
| State | Statute reading (WheelsBack) | NCSL group | Same? |
|---|---|---|---|
| Alabama | Mandatory only above a high-BAC threshold | All offenders | differs |
| Alaska | Mandatory after any first offense | All offenders | yes |
| Arizona | Mandatory after any first offense | All offenders | yes |
| Arkansas | Mandatory after any first offense | All offenders | yes |
| California | Court's discretion or restricted-license condition | Discretionary | yes |
| Colorado | Mandatory only above a high-BAC threshold | All offenders | differs |
| Connecticut | Mandatory after any first offense | All offenders | yes |
| Delaware | Mandatory after any first offense | All offenders | yes |
| District of Columbia | Mandatory after any first offense | All offenders | yes |
| Florida | Mandatory only above a high-BAC threshold | High BAC + repeat | yes |
| Georgia | Court's discretion or restricted-license condition | Repeat only | yes |
| Hawaii | Mandatory after any first offense | All offenders | yes |
| Idaho | Mandatory after any first offense | All offenders | yes |
| Illinois | Court's discretion or restricted-license condition | All offenders | differs |
| Indiana | Court's discretion or restricted-license condition | Discretionary | yes |
| Iowa | Court's discretion or restricted-license condition | All offenders | differs |
| Kansas | Mandatory after any first offense | All offenders | yes |
| Kentucky | Court's discretion or restricted-license condition | All offenders | differs |
| Louisiana | Mandatory after any first offense | All offenders | yes |
| Maine | Court's discretion or restricted-license condition | Repeat only | yes |
| Maryland | Mandatory after any first offense | All offenders | yes |
| Massachusetts | Court's discretion or restricted-license condition | Repeat only | yes |
| Michigan | Mandatory only above a high-BAC threshold | High BAC + repeat | yes |
| Minnesota | Court's discretion or restricted-license condition | High BAC + repeat | differs |
| Mississippi | Court's discretion or restricted-license condition | All offenders | differs |
| Missouri | Mandatory only above a high-BAC threshold | Repeat only | differs |
| Montana | Court's discretion or restricted-license condition | Discretionary | yes |
| Nebraska | Mandatory after any first offense | All offenders | yes |
| Nevada | Mandatory after any first offense | Discretionary | differs |
| New Hampshire | Court's discretion or restricted-license condition | All offenders | differs |
| New Jersey | Mandatory after any first offense | All offenders | yes |
| New Mexico | Mandatory after any first offense | All offenders | yes |
| New York | Mandatory after any first offense | All offenders | yes |
| North Carolina | Mandatory only above a high-BAC threshold | High BAC + repeat | yes |
| North Dakota | Court's discretion or restricted-license condition | Discretionary | yes |
| Ohio | Court's discretion or restricted-license condition | Repeat only | yes |
| Oklahoma | Mandatory after any first offense | All offenders | yes |
| Oregon | Mandatory after any first offense | All offenders | yes |
| Pennsylvania | Mandatory only above a high-BAC threshold | High BAC + repeat | yes |
| Rhode Island | Mandatory only above a high-BAC threshold | High BAC + repeat | yes |
| South Carolina | Mandatory after any first offense | All offenders | yes |
| South Dakota | Court's discretion or restricted-license condition | Discretionary | yes |
| Tennessee | Mandatory after any first offense | All offenders | yes |
| Texas | Mandatory only above a high-BAC threshold | All offenders | differs |
| Utah | Mandatory after any first offense | All offenders | yes |
| Vermont | Court's discretion or restricted-license condition | All offenders | differs |
| Virginia | Court's discretion or restricted-license condition | All offenders | differs |
| Washington | Mandatory after any first offense | All offenders | yes |
| West Virginia | Mandatory only above a high-BAC threshold | All offenders | differs |
| Wisconsin | Mandatory only above a high-BAC threshold | High BAC + repeat | yes |
| Wyoming | Mandatory only above a high-BAC threshold | High BAC + repeat | yes |
Which number should you use?
Say what you are counting. “States where a first offender must install a device to drive at all” and “states where a first offender must install one to drive during the suspension” are different claims, and both are true of different lists. For a citable figure, use the statute reading above and link the state page, which quotes the section it rests on; or download the full dataset (CSV, CC BY 4.0) and apply your own definition to the raw values.
Related: the full comparison table and map · how each value is verified
Not legal advice. WheelsBack provides general information about state laws and agency procedures for reference only. It is not legal advice, does not create an attorney–client relationship, and does not describe how any rule applies to a particular person or case. Laws and fees change; the cited primary source controls. Consult a licensed attorney in the relevant state about a specific situation. Full disclaimer, privacy policy, and disclosures.