Eastern Iowa Criminal Defense Attorneys

Evidence the Prosecutor Might Use in an OWI Case

In an alleged operating while under the influence (OWI) case, the prosecutor has the burden of proving every element of the offense beyond a reasonable doubt. If the prosecutor meets this burden, the judge or jury may find the defendant guilty. If they do not, the trier of fact may return a not guilty verdict.

For the prosecutor to prove guilt, they will present various pieces of evidence. Evidence can range from the arresting officer’s observations to chemical test results.

Although the prosecutor might have support for their arguments that the defendant violated the state’s OWI law, that does not mean a conviction is certain. Defense counsel may present their own evidence countering the prosecutor’s allegations and casting doubt in the minds of the judge or jury.

If you have been charged with OWI in Iowa City, contact Keegan, Tindal & Jaeger at (319) 499-5524 today.

The Elements of an Iowa OWI

As mentioned earlier, the prosecutor must prove every element of the offense to obtain a conviction. The elements of an OWI are listed in Iowa Code § 321J.2.

They include:

  • Operating a motor vehicle while
  • Under the influence of drugs and/or alcohol, or
  • With an alcohol concentration of 0.08 or more.

The evidence the prosecutor presents may depend on whether they are attempting to prove that the defendant was impaired or had an elevated alcohol concentration.

Evidence to Prove Impairment

The prosecutor might argue that the defendant was under the influence of alcohol and/or drugs. To be under the influence means that the driver’s normal faculties were compromised, impacting their ability to safely operate their vehicle.

A person may be considered impaired if alcohol and/or drugs affected any of the following:

  • Reasoning
  • Mental abilities
  • Judgment
  • Emotions
  • Coordination
  • Motor skills

The prosecutor may try to prove impairment in several different ways. They could have the officer testify regarding their observations before and during the stop. For instance, the officer might report that they saw the driver weaving between lanes or disobeying traffic signals, prompting them to pull the individual over. The officer might also note that during the initial contact with the driver, they noticed that the individual had bloodshot eyes and gave unclear responses to questions.

The prosecutor might also rely on the officer’s observations of the driver’s performance on field sobriety tests (FSTs).

Clues of impairment on the three standardized FSTs include, but are not limited to:

  • Horizontal gaze nystagmus:
    • Eyes jerking as they follow a stimulus to one side of the face
    • Eye jerking begins before reaching 40 degrees
  • Walk and turn test:
    • Not taking the required number of steps in either direction
    • Not walking heel-to-toe
  • One leg stand test:
    • Dropping the lifted foot during the 30-second count
    • Hopping to balance

Evidence to Prove Alcohol Concentration

Alcohol concentration refers to the amount of alcohol in a person’s body. It can be determined by administering a blood, breath, or urine test. Thus, the prosecutor might rely on the results of the analysis to prove that the defendant had an alcohol concentration of 0.08 or higher.

Under Iowa’s implied consent law, a person lawfully arrested for suspicion of driving while under the influence is deemed to have given permission to provide a sample for analysis. However, the individual can refuse to submit a specimen, and no test will be given.

Yet, that refusal can come with consequences. It can result in an administrative suspension of driving privileges. A judge or jury may also consider the refusal when determining whether the defendant is guilty.

Challenging OWI Evidence

The defendant can challenge the evidence the prosecutor presents in an OWI case. Defenses that can be raised depend on the facts.

Possible counterarguments that could be mounded include:

  • Inaccuracy of chemical test results: Factors such as not properly calibrating or updating the machine, not following the correct procedures, or the driver having trace amounts of alcohol in their mouth (because they used, for instance, a product like mouthwash that contains alcohol) can affect the analysis and skew the results.
  • Inaccuracy of FSTs: The officer might have noted clues of impairment not because the driver was under the influence, but because the tests were not administered under ideal conditions, the instructions were not clear, or the driver had a medical condition affecting performance, among other variables.
  • No reasonable suspicion for a stop or probable cause for an arrest: The officer might not have had articulable justification to pull over the driver or take them into custody. The defense can move to have the court deem evidence inadmissible because of the unlawful stop or arrest.

Fight Your OWI Charge

Our Iowa City team can assess your case to build a compelling defense on your behalf.

To get started, please call Keegan, Tindal & Jaeger at (319) 499-5524 or contact us online today.