Iowa OWI law — the full guide

The statute: Iowa Code 321J.2

Iowa's drunk-driving statute is Iowa Code 321J.2. A person commits OWI by operating a motor vehicle while:

• Under the influence of an alcoholic beverage or other drug or a combination of such substances, or
• Having an alcohol concentration of 0.08 or more, or
• Having any amount of a controlled substance present in the person, as measured in blood or urine.

"Operating" in Iowa is broad. You can OWI while parked — see actual physical control below.

The 12-year lookback

Iowa counts prior OWI convictions — and deferred judgments — within the previous 12 years for enhancement purposes. A 2014 OWI plus a 2026 OWI = a second offense. A 2013 OWI plus a 2026 OWI = a first offense (just outside the window).

Penalties by offense level

First offense — serious misdemeanor

Second offense — aggravated misdemeanor

Third or subsequent — Class D felony

The 0.15 enhancement

If your tested BAC was 0.15 or higher, several things change:

• You are not eligible for a deferred judgment on a first offense.
• Some judges impose enhanced jail time even on a first offense.
• Insurance and DOT consequences are typically more severe.

Because the 0.15 line carries this much weight, many first-offense defenses focus on whether the test result that put you over 0.15 was correctly obtained.

Deferred judgment — first-offense path

Iowa Code 907.3 lets a judge defer entry of judgment on a first-offense OWI when:

• BAC was under 0.15
• No prior OWI (or deferred) within 12 years
• No accident causing injury or death
• You complete the substance evaluation, DDC, probation, and any other conditions

If you complete probation, the case is dismissed. The arrest and deferral remain visible to certain agencies (FAA, DOT, military, law enforcement, some licensing boards), but the conviction does not appear on a standard criminal record. Iowa allows expungement of the deferred case after the probation discharge in many situations.

The 10-day ALR rule — your license clock

Iowa's Administrative License Revocation (ALR) is a separate, civil DOT process. It moves whether or not the criminal case progresses.

At the ALR hearing, an administrative law judge looks at narrow issues: was there reasonable grounds to believe OWI, was implied consent properly invoked, was the test properly administered or refused. The criminal "beyond a reasonable doubt" standard does not apply.

Temporary Restricted License (TRL)

Even during revocation, Iowa allows a Temporary Restricted License for work, school, medical care, child-care transportation, court-ordered programs, and substance-abuse treatment. For a first-offense OWI you generally must wait through an initial period (typically 30 days, longer in some scenarios) and then apply with the DOT. Ignition interlock is required for the TRL.

Implied consent — Iowa Code 321J.6

By driving on Iowa roads, you've impliedly consented to chemical testing of breath, blood, or urine when an officer has reasonable grounds to believe you've been operating under the influence and one of several triggering conditions exists (accident causing injury, refusal to take a preliminary breath test (PBT), arrest for OWI, etc.). The officer reads the implied-consent advisory, and you decide.

Refusal — the trade-offs

• First refusal: 1-year license revocation.
• Second refusal: 2-year license revocation.
• Refusal is admissible against you at the criminal trial.
• Refusal denies the prosecution a BAC number — sometimes that complicates their case, sometimes not.

There is no universal "always refuse" or "always blow" answer. The right answer depends on whether you've been drinking, whether you have prior OWIs, your job, and other facts. The decision has to be made in the back of a squad car, often with no chance to call a lawyer first.

The chemical test process

Preliminary breath test (PBT) vs evidentiary test

The PBT is the roadside handheld breath device. It's used to establish probable cause — the result is generally not admissible at trial as substantive evidence of BAC. The evidentiary test is the one administered after arrest, typically on a DataMaster instrument at the police station. That result is the one the prosecution will use.

The 15-minute observation period

Before the evidentiary breath test, the operator must observe you for a minimum of 15 minutes with no eating, drinking, smoking, vomiting, or burping. The rationale: residual mouth alcohol or stomach reflux can spike a breath result. If the observation was not actually conducted, the test result may be excluded.

DataMaster calibration

Iowa breath instruments are subject to periodic accuracy checks (commonly cited as a 180-day cycle). If the calibration log for the instrument used in your case shows a gap or a failed check around your test date, the result may be excludable. A defense attorney will subpoena the maintenance logs.

Blood vs breath vs urine

• Breath: fastest, but vulnerable to mouth-alcohol, RFI, and calibration challenges.
• Blood: most accurate; usually drawn at a hospital with chain-of-custody documentation. Often used in serious-injury or fatality cases.
• Urine: primarily for drug detection; not preferred for alcohol because of lag time.

"Operating" while parked — actual physical control

Iowa interprets "operating" broadly. Sitting in the driver's seat with the keys in the ignition — even with the engine off and even while asleep — can support an OWI charge under the doctrine of actual physical control. Common scenario: someone pulls into a parking lot to "sleep it off" and wakes up to flashing lights. Whether actual physical control exists is fact-specific (location of keys, position of seat, whether the engine had been running) and is litigable.

Drug OWI and marijuana

Iowa is a zero-tolerance state for controlled substances behind the wheel. Any detectable amount of a Schedule I substance — including THC metabolites — in blood or urine can support an OWI conviction, with no impairment showing required. Recreational marijuana is not legal in Iowa as of mid-2026; Iowa has a limited medical CBD program, but holding a card does not exempt a driver from drug-OWI prosecution.

Prescription drug OWI

Prescription medications taken as prescribed are not automatically zero-tolerance — but if a prescription medication impaired your driving, you can still be charged under the "under the influence" prong of 321J.2. Sleep aids, opioids, and benzodiazepines come up most often.

Common defenses

• Bad stop. No reasonable suspicion = suppression of everything that followed.
• Bad arrest. No probable cause = suppression of test results, statements, and SFST scoring.
• Bad SFST scoring. The Standardized Field Sobriety Tests have rigid NHTSA protocols. Officers regularly miss steps.
• 15-minute observation not actually observed. Video and dashcam often disprove what the officer wrote.
• DataMaster calibration gap. Subpoena the instrument's maintenance log.
• Mouth alcohol / GERD / dental work. Can spike a breath reading without raising true BAC.
• Rising BAC. If alcohol was still being absorbed at the time of driving, BAC at the wheel may have been below 0.08.
• Implied-consent advisory defective. If the officer misread the advisory or skipped required language, both the criminal test result and the ALR revocation can fail.
• Independent test refused. Iowa drivers have the right to an independent test at their own expense; obstruction of that right can taint the case.

Felony OWI thresholds in summary

• Third OWI within 12 years: Class D felony.
• OWI causing serious injury: Class D felony (Iowa Code 321J.2(8)).
• OWI causing death: Class B felony (homicide by vehicle, Iowa Code 707.6A) — up to 25 years.

Vehicle forfeiture for repeat offenders

Iowa Code 321J.4B authorizes forfeiture of the vehicle used in the offense for certain repeat offenders. The vehicle does not have to be owned by the driver to be subject to seizure, though innocent-owner protections exist.

FAQ — Iowa OWI statute