Blew a .15 or Higher in Missouri? What a High BAC Changes in a DWI Case

If you were arrested for a high BAC DWI in Missouri, the number on your test can change the minimum jail time a judge must impose. For a first offense, Missouri law sets a required term of not less than 48 hours when the result was .15 to .20, and not less than five days when it was above .20. That rule is tied to how a first offense qualifies for a suspended imposition of sentence (SIS), so it does not apply automatically in every case.

Two other points matter just as much. A high number does not, by itself, turn a first offense into a felony. And a test result is evidence, not a conviction. It can be challenged.

This post explains the high-BAC rule. For the full penalty picture, see our DWI Penalties page.

High BAC DWI in Missouri: .15 and .20 minimum jail time at a glance

The high-BAC rule appears in two statutes with identical wording: RSMo 577.010 (driving while intoxicated), subsection 5, and RSMo 577.012 (driving with excessive blood alcohol content), also subsection 5. As of 2026, it works like this for a first offense:

A few details are worth knowing:

• The tiers are not ".15–.199" and ".20+". The statute says "fifteen-hundredths to twenty-hundredths" for the 48-hour tier and "greater than twenty-hundredths" for the five-day tier. On that wording, a result of exactly .20 falls in the 48-hour tier.
• The wording is different from the repeat-offender rules. Subsection 5 says the "required term of imprisonment shall be not less than" 48 hours or five days. The repeat-offender provisions, covered below, are written in terms of eligibility for probation or parole.
• It applies to both charges. People are often charged under both 577.010 and 577.012, and the same tiers appear in each.

How the high-BAC minimum fits with an SIS

The 48-hour and five-day terms apply when a person "is not granted a suspended imposition of sentence for the reasons described in" subsection 3 of 577.010 (or subsection 4 of 577.012). So the SIS rules come first.

Under those subsections, a person found guilty of a first offense cannot be granted an SIS:

1. Unless the person is placed on probation for at least two years; or
2. In a circuit where a DWI court or docket, or another court-ordered treatment program, is available and the offense was committed at .15 or more, unless the person takes part in and successfully completes that program.

In practical terms, a first offender with a .15 or higher result in a circuit that has a DWI court or treatment program available generally has to go through that program to receive an SIS. How courts apply subsection 5 in a particular case, including which SIS denials trigger the 48-hour or five-day term, is a question an attorney can answer once they know your circuit and your facts. Our post on what an SIS means for a DWI in Missouri explains the SIS itself in more detail.

What a DWI court is

RSMo 478.001 defines a DWI court as a treatment court focused on the substance use disorder of defendants who have pleaded guilty to, or been found guilty of, DWI or excessive BAC. The statute says any circuit court may establish one. It also says that on successful completion of a treatment court program, the charges or penalty "may be dismissed, reduced, or modified, unless otherwise stated." That is a possibility, not a promise.

No community-service substitute in the high-BAC rule

Subsection 5 contains no community-service alternative to the 48-hour or five-day term. Community service appears in the statute only in the prior and persistent offender provisions.

When you have prior offenses

If you have earlier intoxication-related traffic offenses, a different set of rules takes over. Those rules are in RSMo 577.010.6 and 577.012.7, and the offender categories are defined in RSMo 577.001. For a prior, persistent, aggravated, chronic or habitual offender, the court cannot grant an SIS or impose a fine in place of imprisonment.

The high-BAC subsection is written around first offenses. The statutes do not say that the 48-hour or five-day terms are added on top of these repeat-offender minimums. If you have a prior record, an attorney should review exactly how your earlier cases are counted.

What a high BAC does not change

The charge level

Under 577.010.2, a first DWI is a class B misdemeanor. It becomes a class A misdemeanor for a prior offender or when a person under 17 is in the vehicle, and it becomes a felony based on offender status or injury to another person. The excessive BAC classes in 577.012.3 follow offender status. BAC level does not appear in any of these classifications, so a .15 or .25 result on its own does not make a first offense a felony.

The administrative license suspension

The Department of Revenue's suspension or revocation under RSMo 302.505 turns on whether there was probable cause to believe you were driving at .08 or more (lower thresholds apply to drivers under 21). Nothing in that section increases with a higher number. The statute also says this license case is separate from the criminal case, and that the outcome of the criminal charges does not affect the suspension.

The length of the suspension and other license consequences are set by other statutes. See our License Suspension and Reinstatement page, and ask an attorney which rules apply to your record.

Why the number itself can be contested

Because the 48-hour and five-day terms depend on the exact result, the reliability of that result matters. Under RSMo 577.037, a chemical test must be performed as provided in sections 577.020 to 577.041 and in accordance with methods and standards approved by the Department of Health and Senior Services. Only then does it carry the legal effect the statute gives it. Section 577.012.2 also requires testing under those sections.

The Department's breath-testing rules (19 CSR 25-30) include, as of 2026:

• A 15-minute observation period. This is a continuous period that ends when the breath sample is given. The operator must stay close enough to reasonably ensure, by sight, hearing or smell, that the person does not smoke, vomit or take anything by mouth. The rule states that direct observation is not necessary. The observation must be done by a holder of a current Type II or Type III permit.
• Maintenance checks. These are required at intervals of no more than 35 days, with the report sent to the Department within 15 days. A check is also required when an instrument is put into service.
• Approved instruments. The rules list the Alco-Sensor IV with printer, Intox EC/IR II, Intox DMT and Intoxilyzer Model 8000.
• Recording results as displayed. The rules give the example that a reading of 0.149 is recorded as .149. It is not rounded up to .15.

Whether any issue exists depends on the facts. An attorney can review the police report, the breath ticket, the operator's permit and the instrument's maintenance records, or the blood-test documentation. Our DWI Defense page explains more about how these cases are handled.

Talk to a lawyer about your test result

A .15 or .20 result raises real questions about jail time, an SIS and treatment court. The answers depend on your record, your circuit and the evidence. To talk with The DWI Guys, call 314-827-6222 or reach us through our contact page.

This post is general information about Missouri law, not legal advice for your situation.