Missouri DWI & DUI Laws
BAC limits, penalties, license suspension periods, and ignition interlock requirements for Missouri drivers.
State Guide
Missouri DWI Laws at a Glance
In Missouri, impaired driving is charged as DWI, with a standard BAC threshold of 0.08%. The consequences that follow, suspension length, interlock requirements, how far back prior offenses count, are all set by state law and vary widely from state to state.
| Detail | Missouri Rule | Notes |
|---|---|---|
| Statutory Term | DWI | The specific offense name and code section vary by state |
| Standard BAC Limit | 0.08% | The standard threshold used in nearly every state |
| First-Offense License Suspension | 1 month | Administrative and criminal suspensions can run separately; actual length depends on case specifics |
| Ignition Interlock Device | Conditional | Required for high-bac or repeat offenders, but not automatically for a standard first offense |
| Lookback Period | Not consistently published | Confirm the current lookback window against state code. This figure is not consistently published across states |
How BAC Testing and Implied Consent Work
Every state uses a breath, blood, or urine test to measure blood alcohol concentration, and every state has an "implied consent" law: by driving on public roads, you've already agreed to testing if lawfully arrested for suspected impairment. Refusing a test carries its own separate penalties, usually an automatic license suspension, regardless of whether you're ultimately convicted of DWI.
License Suspension: Two Separate Tracks
Missouri, like many states, separates the administrative side (a motor vehicle agency suspension that can start almost immediately after arrest) from the criminal case working through court. The administrative and first-offense suspension period in Missouri is 1 month.
Common Questions
Frequently Asked Questions: DWI in Missouri
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What is the BAC limit in Missouri?Missouri's standard illegal BAC threshold is 0.08%. This matches the standard used in nearly every U.S. state. Commercial drivers and drivers under 21 face lower thresholds in every state, including Missouri.
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How long is a license suspended for a first DWI offense in Missouri?Missouri's first-offense suspension period is generally 1 month. This can involve both an administrative suspension (handled by the state's motor vehicle agency, often starting soon after arrest) and consequences tied to the criminal case itself, which can run on a different timeline.
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Does Missouri require an ignition interlock device?In Missouri, an ignition interlock device is required for high-BAC or repeat offenders, but not automatically for a standard first offense. Requirements can also depend on whether a high BAC was involved or whether it's a repeat offense.
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What does "DWI" mean in Missouri?DWI is Missouri's statutory term for operating a vehicle while impaired by alcohol or drugs above the legal threshold. Different states use different terms (DUI, DWI, OWI, OUI, OVI, and others) for what is fundamentally the same category of offense, though the exact legal definitions and penalty structures differ by state.
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What happens if I refuse a BAC test in Missouri?Like every state, Missouri has an implied consent law: refusing a lawfully requested BAC test after a DWI arrest triggers its own penalty, typically an automatic license suspension, separate from and in addition to any penalty from the underlying charge itself.
Sources & References
- National Highway Traffic Safety Administration, Drunk Driving official program overview
- Insurance Institute for Highway Safety, Alcohol Interlock Laws by State
- Missouri BAC limit, suspension period, and interlock requirement figures compiled from published state-by-state legal reference tables; confirm current figures against official MO state code before relying on them
- Governors Highway Safety Association, Alcohol-Impaired Driving State Laws