Should an Iowa OWI (DUI) test subject refuse the Datamaster DMT?

by DAC-LAW PLC


When a test subject refuses the Datamaster DMT, they deny to the State evidence of the presumptive level of intoxication, one way to be convicted of Operating While Under the Influence in the State of Iowa.

That’s because Model Jury Instruction 2500.1 allows the State to prove that a defendant is Operating While Under the Influence (OWI) if they are merely over the .08 BrAC/BAC/UAC.

However, in Iowa, an OWI defendant may also be found guilty irrespective of BrAC/BAC/UAC if one or more of the following are true:

1.         [His] [Her] reason or mental ability has been affected.

2.         [His] [Her] judgment is impaired.

3.         [His] [Her] emotions are visibly excited.

4.         [He] [She] has, to any extent, lost control of bodily actions or motions.

Iowa Model Criminal Jury Instruction 2500.5

Thus, a Datamaster DMT breath test result is not necessary to convict a defendant of OWI in the State of Iowa.


However, by Iowa law, Iowa Code § 321J.7, the Datamaster DMT breath test result is presumed to be the BrAC/BAC of the defendant within two hours of operation:

“The alcohol concentration established by an analysis of a sample of a person's [blood] [breath] [urine] withdrawn within two hours after the person operated a motor vehicle is presumed to be the alcohol concentration at the time [he] [she] operated the motor vehicle.


If you find the defendant was operating a motor vehicle and a sample of [his] [her] [blood] [breath] [urine] was withdrawn within two hours after that operation, you may, but are not required to, conclude that the alcohol concentration established by the analysis of the sample was the alcohol concentration at the time [he] [she] operated the motor vehicle.”

Iowa Model Criminal Jury Instruction 2500.4

So a refusal will deny to the prosecution that presumption. However, the jury is also allowed to include in its deliberations a refusal:

“The defendant was asked to give a [breath] [blood] [urine] sample so it could be analyzed to determine the percent of alcohol in [his] [her] blood.  [The defendant refused.]  [It is alleged the defendant refused.]

 A person is not required to give a sample of any bodily substance; however, you may consider a refusal in reaching your verdict.”

You might think that you’re “damned if you do and if you don’t.” The law is mostly concerned with ruling out a false positive. In other words, if a defendant is asked to provide a sample because the officer has reasonable grounds to believe they are operating while under the influence, but may be mistaken, and the Datamaster DMT shows they were not impaired, the officer is technically free to refrain from arrest. However, in Linn County the officers typically arrest a defendant before they request a Datamaster DMT, and they will likely not “unarrest” someone. So it may also be necessary to request an independent chemical test to show that the test subject is under the influence of no intoxicants. Be mindful that any controlled substance in the blood, including THC or other marijuana metabolite, will be sufficient to prove intoxication even if the test subject is not “high.”

The conventional wisdom is that it takes more time to metabolize alcohol than to consume it. Makes sense, right? That’s because alcohol is directly absorbed into the stomach lining but the body takes longer to dispose of it. That’s why people become intoxicated—because alcohol is toxic and it is not immediately disposed. Generally speaking, law enforcement will tell you that every “drink,” whether it is a 12 ounce beer, a mixed drink, or a shot of hard liquor, includes the equivalent of .02 grams of ethanol per 210 L breath, or, 100 mL breath, or 67 mL urine, roughly speaking, since individual differences in weight and metabolization.

So if a person does the rough arithmetic necessary to determine whether a test is necessary, they might conclude that consent is appropriate, with the understanding that they will request an independent chemical test if it exceeds the presumptive level of intoxication in Iowa. However, if they know they have absorbed and failed to dissipate four or more drinks, a refusal may be appropriate.

If you or a loved one has been arrested for OWI in the State of Iowa, contact DAC-LAW PLC at 319-389-4276 or https://www.cedarrapidsduilawyer.lawyer.





Conventional Wisdom the body immediately absorbs alcohol through the lining of the stomach and dissipates it about one drink an hour, whether that one drink is a shot of hard liquor, a twelve ounce beer, or a mixed drink. Roughly speaking, if a test subject believes that they have not dissipated the alcohol from four or more drinks, a refusal may be appropriate. However, the State may present both the refusal and other signs of impairment to the jury to prove intoxication in the State of Iowa. If a test subject questions the Datamaster DMT test result, they are entitled to request an independent chemical test at their own expense.