Ignition interlock requirements in Missouri

Missouri gives the court a choice after a first offense and none after a second. The device runs at least six months from reinstatement — and at almost every point where the device unlocks driving, the insurance filing is the gate in front of it.

A court decides first, and the number of offenses decides how much it can choose

Missouri's general interlock section draws its line at the second offense. For a first intoxication-related traffic offense the court may order a device; for a second or subsequent one it shall. Either way the order runs “for a period of not less than six months from the date of reinstatement of the person's driver's license.”

The six months are measured from reinstatement, not from the offense or the conviction. A license that is suspended for months before it comes back starts the device clock late. And the same section requires a device on every vehicle the person drives as a condition of any limited driving privilege granted after a second or subsequent offense.

Where the device and the SR-22 meet

Missouri ties the two together at more than one point, and in each the insurance filing is the gate.

The restricted driving privilege

A restricted driving privilege after an administrative alcohol suspension “shall not be issued until he or she has filed proof of financial responsibility with the department of revenue, in accordance with chapter 303.” The privilege itself states whether a device is a condition of driving.

A device instead of a points suspension

The points section offers a trade. A person who would otherwise be suspended, and who files proof that every vehicle they drive has a certified device, has “no period of suspension”: they complete a ninety-day restricted driving privilege instead. At the end of the ninety days the license is reinstated — upon filing proof of financial responsibility under chapter 303. If the monitoring reports show a confirmed reading above the set point or tampering during the ninety days, reinstatement waits for a further thirty days of restricted driving.

Failing to keep either proof — the device or the filing — re-suspends the license. Those are two separate obligations, and the section treats a lapse in either the same way.

The filing that follows

The proof of financial responsibility these sections require is the filing described on the Missouri SR-22 page: 25/50/25, for 2 years with a clean record. The device period and the filing period are counted from different dates and almost never end together.

Reinstatement after a long denial: six months, then three clean months

For a person reinstated after the longer license denials in section 302.060, the device is a condition of reinstatement and must have a photo identification feature; a court may also require GPS. It stays on every vehicle the person drives for at least six months after reinstatement — and if the monitoring reports show a confirmed reading above the set point, or tampering, within the last three months of that period, the period extends “until the person has completed three consecutive months with no violations.”

The end of the requirement is therefore earned rather than dated: the last three months must be clean.

Proof to the court, and what the court can do about cost

When a court orders a device, the person must prove compliance to the court or the probation officer within thirty days of the order. Without proof, and without a finding of good cause, the court revokes or terminates probation or the limited privilege. The person reports on the device at least once a year, pays for it and its maintenance, and is liable for replacement if it is broken, destroyed or stolen; the court requires periodic calibration checks.

One sentence in the same section is easy to miss and worth asking about: if a court imposes both a fine and a device for the same offense, “the amount of the fine may be reduced by the cost of the ignition interlock device.”

Driving for work in an employer's vehicle

A person ordered to use a device may apply to the court for an employment exemption variance to drive an employer-owned vehicle without one, for work only. The section closes the obvious loophole: no variance for anyone self-employed, or who owns or controls the business that owns the vehicle, and none for an employer vehicle used to carry children or vulnerable persons, or for personal use.

What this page does not cover

Missouri's DWI offense levels, jail and fine terms, and the device certification rules are in chapter 577 and in regulations this site has not read. Device prices are set by providers, not by statute.

Common questions