Missouri DWI Laws

The per se limit is 0.08% — driving with that much alcohol in your blood is a crime by itself (§ 577.012.1(1)), and commercial drivers face a 0.04% limit (§ 577.012.1(2)). You can also be charged below 0.08% under the impairment-based DWI statute (§ 577.010), which requires no test number at all and covers alcohol, drugs, or any combination. Missouri has an unusual protection here: if a chemical test shows less than 0.08%, the alcohol-intoxication charge must be dismissed with prejudice — unless too much time passed between driving and testing, there is evidence of drug influence, or there is substantial other evidence of intoxication from witnesses or your own admissions (§ 577.037.2). For drivers under 21, a 0.02% threshold triggers an administrative license action but is not a separate crime (§ 302.505.1).

A first DWI is a class B misdemeanor: up to six months in jail and up to a $1,000 fine, with no mandatory minimum jail and no minimum fine for a typical case below 0.15% BAC (§§ 577.010.2(1), 558.011.1(7), 558.002.1(3)). Every finding of guilt requires completing the substance abuse traffic offender program at your own expense (§ 302.580). A first conviction adds 8 points and triggers a 30-day license suspension followed by a 60-day restricted driving privilege — or you can instead serve a 90-day interlock-restricted privilege with no suspension at all (§§ 302.302.1(8), 302.304.5). A suspended imposition of sentence is possible but requires at least two years of probation, and at 0.15% BAC or more it also requires completing a DWI-court or treatment program where available (§ 577.010.3). A passenger younger than 17 raises the charge to a class A misdemeanor (§ 577.010.2(2)(b)).

At 0.15% BAC or more, a first offender who does not receive a suspended imposition of sentence must serve at least 48 hours in jail; above 0.20% — strictly greater than, so exactly 0.20% stays in the 48-hour band — the minimum rises to five days (§§ 577.010.5, 577.012.5). Getting a suspended imposition of sentence at 0.15% or more requires participating in and completing a DWI-court or other court-ordered treatment program where one is available (§ 577.010.3(2)). A high BAC also limits the court's power over the substance-abuse-program assignment: at 0.15% or more the court may modify but not waive the education or rehabilitation assignment (§ 302.304.14). A separate 0.18% threshold applies only to death cases, where it makes the offense a class B felony (§ 577.010.2(6)(e)).

A second offense within five years of a prior makes you a "prior offender": a class A misdemeanor with up to one year in jail and up to a $2,000 fine, no suspended imposition of sentence, and no fine in lieu of jail (§§ 577.001(20), 577.010.2(2)(a), .6(1)). You must serve at least ten days before becoming eligible for probation or parole, unless you complete at least 30 days of community service or a DWI-court program (§ 577.010.6(2)). The conviction adds 12 points, which revokes your license for one year (§§ 302.302.1(9), 302.304.7), and an ignition interlock device is mandatory for at least six months after reinstatement (§ 302.440). If both convictions fall within five years, a separate five-year license denial applies (§ 302.060.1(10)). If your prior is older than five years, the new charge is a first offense criminally — but the license-side counters run on their own clocks.

Yes. Two or more prior intoxication-related traffic offenses — with no time limit — make you a "persistent offender," and the third offense is a class E felony: up to four years in prison, up to a $10,000 fine, and at least 30 days served before probation or parole eligibility unless you complete 60 days of community service or a DWI-court program (§§ 577.001(18), 577.010.2(3)(a), .6(3), 558.011.1(5), 558.002.1(1)). The ladder keeps climbing: a fourth offense ("aggravated") is a class D felony with up to seven years and a 60-day floor with no alternatives; a fifth ("chronic") is a class C felony with three to ten years and a two-year floor; a sixth or later ("habitual") is a class B felony with five to fifteen years, a two-year floor, and no fine authorized at all (§§ 577.001, 577.010.2, .6, 558.011.1, 558.002.1). One prior DWI in which someone was injured or killed makes your next offense a felony by itself (§ 577.001(18)(b)).

It depends on the rung. The five-year window applies only to the second-offense "prior offender" misdemeanor — one prior that occurred within five years of the new offense, measured occurrence to occurrence (§ 577.001(20)). From the third offense up, every prior intoxication-related traffic offense counts for life (§ 577.001(18), (1), (5), (11)). Qualifying priors include offenses under state law, county or municipal ordinances, federal law, and military law (§ 577.001(15)); boating offenses do not count — they have their own separate ladder. Watch the separate license-side clocks too: a five-year "alcohol-related enforcement contact" window controls the administrative track (§ 302.525.2), two convictions within five years trigger a five-year license denial (§ 302.060.1(10)), and more than two convictions ever trigger a ten-year denial (§ 302.060.1(9)).

Missouri runs two parallel tracks. The administrative track starts with the arrest itself: with no alcohol-related enforcement contact in the preceding five years, you get a 30-day suspension followed by a 60-day restricted driving privilege — or you can install an ignition interlock device and serve a 90-day interlock-restricted privilege with no suspension (§ 302.525.2(1)); with a prior contact within five years, it is a one-year revocation with an interlock-only restricted privilege (§ 302.525.2(2)-(3)). The conviction track then adds points: a first conviction is 8 points (the same 30-day-plus-60-day structure), and a second intoxication conviction is 12 points, which revokes the license for one year (§§ 302.302, 302.304.5, .7). The two periods credit against each other — you serve the longer of the two, never the sum (§ 302.525.4). Reinstatement requires completing the substance abuse traffic offender program, proof of financial responsibility, and $45 in statutory fees ($20 plus $25) (§§ 302.304.12, .14, 302.541.1).

Yes — these are license denials, separate from the suspension and revocation tracks. Two DWI convictions within a five-year period bar the state from issuing you a new license for five years, and a conviction for criminally negligent DWI causing a death triggers the same denial (§ 302.060.1(10)). More than two convictions — lifetime, no window — bar a new license for ten years (§ 302.060.1(9)). Both denials now have a limited-driving-privilege path: install a certified ignition interlock device with a photo-identification feature and show no new alcohol-related contacts, and a court (or the director of revenue) can let you drive for work and other necessities during the denial (§ 302.309.3(8)); drivers convicted of a DWI death are excluded from the five-year-denial privilege. When the denial period ends, reinstatement requires a circuit-court petition with a criminal-history check — and the ten-year petition can only ever be used once (§ 302.060.1(9), .3).

Not automatically on a first offense: the court may order one (§ 302.440), and you will need one if you choose the 90-day interlock-restricted privilege instead of a suspension, or if you need a restricted privilege and have any prior alcohol-related contact (§§ 302.304.5, 302.525.2(3)). For a second or subsequent intoxication-related offense the device is mandatory — for at least six months from the date your license is reinstated — and it is a required condition of any limited driving privilege (§ 302.440). Reinstatement after a revocation, a prior-contact suspension, a refusal, or a § 302.060 denial carries its own six-month interlock requirement, and a violation or tampering in the last three months extends the period until you complete three clean consecutive months (§§ 302.060.2, 302.304.17, 302.525.5, 302.574.10). An employment exemption lets you drive an employer-owned vehicle without a device for work only — not if you are self-employed, and never for personal use (§ 302.441).

Refusal is civil, not a separate crime: the officer takes your license on the spot, issues a 15-day temporary permit, and the director of revenue revokes your license for one year (§ 302.574.1, .3). You can petition the circuit court for review and ask for a stay (§ 302.574.4). If you ask for a lawyer, you get twenty minutes to try to reach one before continued refusal counts (§ 577.041.3) — and the refusal itself is admissible against you at the criminal trial (§ 577.041.1). Reinstatement requires completing the substance abuse traffic offender program, and without proof of financial responsibility the revocation stretches to two years (§ 302.574.7, .11). If you have any prior alcohol-related contact, an ignition interlock device is required for at least six months after reinstatement (§ 302.574.10).

A driver under 21 who is stopped on probable cause and has a BAC of 0.02% or more faces an administrative license suspension or revocation by the department of revenue (§ 302.505.1) — the same 30-day-plus-restricted-privilege or one-year periods that apply to adult administrative actions (§ 302.525.2). This zero-tolerance rule is a license action, not a crime: criminal DWI charges still require a 0.08% BAC or proof of actual intoxication. One break for first-timers: a driver under 21 suspended solely for a first zero-tolerance determination is exempt from the proof-of-financial-responsibility (SR-22) requirement for reinstatement (§ 302.541.2).

Yes. Missouri's "intoxicated condition" covers alcohol, controlled substances, drugs, or any combination (§ 577.001(13)), so you can be charged for driving impaired by marijuana or prescription medication even though the substance itself was legal to use. There is no per se THC or drug number anywhere in the scheme — drug DWI is proven by impairment evidence, and implied consent extends to blood, saliva, and urine testing for drugs (§ 577.020.1). Note that the sub-0.08 dismissal rule does not protect drugged drivers: a low alcohol result does not force dismissal when there is evidence of drug influence (§ 577.037.2(2)).

The felony elevations are built into the DWI statute itself and apply with criminal negligence, regardless of priors: injury is a class E felony; injury to a law enforcement officer or emergency personnel, or serious injury to anyone, is a class D felony; serious injury to an officer or emergency personnel, or any death, is a class C felony; the death of an officer or emergency personnel, of someone who was not a passenger in your vehicle, of two or more people, or any death with a BAC of at least 0.18%, is a class B felony; and repeating any of those death offenses is a class A felony (§ 577.010.2(3)-(7)). Prosecutors may alternatively charge involuntary manslaughter (recklessly causing death, a class C felony, § 565.024). A criminally negligent DWI death also bars issuance of a new driver's license (§ 302.060.1(10)) — and a prior injury or death DWI permanently accelerates the offender ladder, making your next offense a felony by itself (§ 577.001(18)(b)).