Preliminary breath test

Updated: May 31

In Iowa OWI (DUI) prosecutions, a preliminary breath test, or, PBT, is essentially a fourth and final standardized field sobriety test following the horizontal gaze nystagmus (HGN), the Walk and Turn (WAT), and the One Leg Stand (OLS) during a traffic stop.

Once an officer has “reasonable grounds” to believe that the test subject is impaired, he or she may request a PBT. At this point, if the test subject refuses the PBT, the officer may invoke implied consent and temporarily detain and transport the subject back to the stationhouse to seek consent or refusal to the Datamaster DMT breath test, or, blood or urine, at the officer’s discretion.

Most cases that I have been involved with resulted in arrest following a PBT test “failure,” or, in the alternative, a PBT test refusal. Officers are not required to arrest an SFST test subject at the roadside but most Iowa test administrators do so, alleging that their observations constitute not only reasonable grounds to invoke implied consent to a Datamaster DMT test but also the more rigorous probable cause to arrest standard. In other words, they believe they have enough before they even ask for a Datamaster DMT breath test.

Query whether an SFST test administrator will “unarrest” a test subject if he or she consents to a Datamaster DMT and the subject blows under .08 grams ethanol per 210 L breath—or, in the alternative, the officer will follow through with the arrest and argue at jury trial that the Defendant was otherwise impaired, whether by a combination of alcohol and drugs, or by outward observations of the trained officer.

In any case, most test subjects and OWI (DUI) arrestees in Cedar Rapids, Iowa City, Waterloo, Linn, Johnson, Blackhawk, and other Iowa communities and counties confuse the PBT and the Datamaster DMT because both require a test sample.

It’s important to note that the Datamaster DMT, when used for evidentiary purposes, is the result presented to the jury—the PBT as to test result or even presence of alcohol is statutorily prohibited from being presented to the jury. However, it may be presented to a judge if the OWI defendant challenges reasonable grounds to believe the test subject is intoxicated.

Regardless, if you or a loved one has been arrested for OWI (DUI) in Cedar Rapids, Iowa City, Waterloo, Linn, Johnson, Blackhawk, or other Iowa communities or counties, contact us.

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