Many people assume that a breathalyzer provides a definitive answer about whether someone was legally intoxicated. In reality, breath test results are not always as straightforward as they may seem.
Breath testing plays a major role in Michigan OWI investigations, and prosecutors often rely heavily on those results when pursuing charges. However, breath-testing devices estimate blood alcohol concentration rather than directly measuring it. Testing procedures, medical conditions, equipment issues, and human error can all affect the reliability of a breath test result.
If you were arrested for OWI after providing a breath sample, understanding how breath testing works and what can cause inaccurate results may help you better understand the evidence being used against you.
How Breathalyzers Work in Michigan OWI Cases
A breathalyzer does not directly measure the amount of alcohol in your bloodstream. Instead, it analyzes alcohol detected in your breath and uses a formula to estimate your blood alcohol concentration (BAC).
To make that estimate, the device relies on a standardized breath-to-blood ratio. The problem is that not everyone processes alcohol the same way. Individual differences in physiology can affect the relationship between the alcohol in your breath and the alcohol in your blood.
Factors that may influence a breath test result include:
- Body temperature
- Breathing patterns
- Lung capacity
- Recent alcohol consumption
- Certain medical conditions
Because breath testing relies on estimates and assumptions, breath test results are not always immune to challenge.
What Can Cause an Inaccurate Breathalyzer Reading?
If you provided a breath sample, the accuracy of the result depends on more than the testing device itself. The testing process can also affect the reliability of the result, and errors may occur even when the machine appears to be functioning properly.
Issues that can affect breath test accuracy include:
- Improper calibration
- Missed observation periods
- Officer error
- Device maintenance problems
- Environmental interference
- Software or hardware issues
When reviewing an OWI case, defense attorneys often examine both the testing device and the procedures used to administer the test.
Medical Conditions Can Produce Inaccurate Breath Test Results
Not every elevated breath test result is caused solely by alcohol consumption. Certain medical conditions can sometimes interfere with breath testing and produce misleading readings.
Acid Reflux and GERD
If you have acid reflux or gastroesophageal reflux disease (GERD), the condition may affect a breath test under certain circumstances. When stomach contents move into the mouth before testing, alcohol that would not normally be present in a breath sample may influence the reported result.
Observation periods are intended to reduce the risk of inaccurate readings caused by mouth alcohol. During that period, officers generally watch for actions that could affect the test result. If alcohol remains in your mouth before testing, contamination may become an issue.
Diabetes and Other Health Conditions
If you have diabetes or another medical condition, certain compounds produced by the body may affect some breath testing methods. Diabetes may cause the body to produce ketones under some circumstances. Those compounds can create concerns about the accuracy of the reported result.
Your medical history may become relevant when evaluating a breath test result. Medical records may help explain whether a health condition contributed to the result.
How to Challenge Breathalyzer Evidence in a Michigan OWI Case
If a breath test result is being used against you, the result is not automatically accepted without review. Our DUI attorneys may examine testing procedures, maintenance records, and information gathered during the investigation.
Reviewing Calibration and Maintenance Records
Breath testing devices require regular maintenance and calibration to operate properly. If a breath test result is being used as evidence against you, records related to the device may become an important part of the review.
Michigan Compiled Laws § 257.625a addresses chemical testing in Michigan OWI cases and includes requirements related to testing procedures. If maintenance records show irregularities or calibration issues, you may have unanswered questions.
Examining How the Test Was Administered
The way a breath test is administered may be just as important as the device itself. Officers are generally expected to follow specific procedures before administering a breath test, including observation requirements designed to reduce the risk of inaccurate results. If an officer does not follow those procedures, this may become a concern.
Small procedural errors do not automatically invalidate a breath test. However, deviations from established testing procedures may become relevant when evaluating the reliability of the result. Observation periods and other testing requirements may become important when reviewing breath test evidence.
Looking for Alternative Explanations for Elevated Results
A higher-than-expected breath test result may have more than one explanation. Medical conditions or environmental influences may affect the alcohol concentration reported by the device. Sometimes, those issues may help explain why a breath test produced an elevated result.
Our team often looks beyond a single explanation when reviewing breath test evidence. A medical condition may become important in one case, while the way the test was administered may deserve closer review in another.
Do Breathalyzer Results Hold Up in Michigan Court?
If the prosecution is relying on a breath test result, that result is only one piece of the evidence. Courts may consider witness testimony, field sobriety testing, officer observations, and concerns about the reliability of the breath test itself when evaluating an OVI case.
Expert testimony may also be important when technical issues arise. Michigan Administrative Code R 325.2655 establishes standards for evidential breath-testing procedures. If the officer administering the test did not follow those standards, questions about reliability or admissibility may become important. Do breathalyzers hold up in court in Michigan? Courts often consider the breath test alongside other evidence gathered during the investigation.
Defense Attorneys Often Examine Evidence Beyond the Breath Test
If the prosecution is relying on a breath test result, that result is only one piece of the evidence. A breathalyzer defense attorney in Michigan with Davis Law Group may examine the entire investigation rather than focusing exclusively on the breath test result. We may review:
- Maintenance and calibration records
- Officer training records
- Observation period compliance
- Medical explanations
- Video evidence
- Police reports
- Witness statements
No two OWI cases are exactly alike. In some cases, the breath test itself may be the primary issue. In others, the circumstances surrounding the traffic stop, the officer’s observations, or the manner in which evidence was collected may raise important questions.
By reviewing the entire investigation rather than focusing on a single piece of evidence, defense attorneys can better evaluate the strengths and weaknesses of the prosecution’s case and identify potential defenses that may not be immediately obvious from the breath test result alone.
Questions People Often Ask About Breathalyzer Evidence
Can I Refuse a Breath Test in Michigan?
Michigan Compiled Laws § 257.625c contains the state’s implied consent provisions. If you refuse a chemical test in circumstances covered by that law, the refusal may affect your driving privileges even if your OWI case has not been resolved.
Is a Blood Test More Accurate Than a Breath Test?
If you provided a blood sample, the test measured alcohol directly from your bloodstream rather than estimating it from your breath. However, blood testing and breath testing may present different evidentiary issues. The way a sample was collected or analyzed may become important during a case review.
Are Portable Breath Tests Different From Stationary Breath Testing Devices?
Yes. Officers often use portable breath tests during roadside investigations, while stationary breath-testing devices are generally used later for evidential purposes. The two types of devices may be subject to different testing procedures and evidentiary requirements.
What Should I Do If I Think My Breath Test Result Was Wrong?
If you believe your breath test result was inaccurate, preserve records related to the test. It may also help to document facts you remember about the testing process. Information about a medical condition may become important. The way the test was administered may also be relevant.
Can Prescription Medications Affect an OWI Investigation?
Yes. Prescription medications may affect an OWI investigation in ways that extend beyond breath testing. Some medications may influence officers’ observations or affect other information gathered during the investigation.
Does an OWI Case Automatically Get Dismissed If a Breath Test Is Excluded?
No. Prosecutors may still rely on other evidence even if a breath test result is excluded. Your OWI breath test defense lawyer in Michigan may review the remaining evidence to determine how the exclusion affects your case.
A Breath Test Result Is Not Always the End of the Story
A breathalyzer result can be powerful evidence in a Michigan OWI case, but it is not automatically beyond challenge. Questions about calibration, maintenance, testing procedures, medical conditions, and other factors may affect how much weight the breath test result deserves.
Just as importantly, prosecutors must often rely on more than a single test result. Officer observations, field sobriety tests, witness statements, video evidence, and other facts gathered during the investigation may all play a role in the case.
If you were arrested for OWI and a breath test is being used against you, an experienced Michigan OWI defense attorney can review the circumstances surrounding the stop, the testing process, and the evidence. Contact Davis Law to discuss your case and learn more about your legal options.