How Can You Challenge the Accuracy of a Breathalyzer Test in DWI Cases?
If you're facing a DWI (Driving While Intoxicated) charge in Missouri, one of the key pieces of evidence the prosecution may use against you is the result of a breathalyzer test. These tests are used to measure your blood alcohol concentration (BAC), and if that number is above the legal limit of 0.08%, it can lead to serious legal consequences.
Missouri courts take DWI charges seriously, but that doesn't mean you have to accept the results of a breath test without question. Many factors can affect the reliability of breathalyzer results. At Jeff Jarrett Law Office in Kansas City, Missouri, I’m an experienced criminal defense attorney who is dedicated to protecting your rights.
Breathalyzer Tests in DWI Cases
Breathalyzer tests are designed to provide a quick estimate of BAC by measuring the amount of alcohol in your breath. Law enforcement officers use these devices during traffic stops to establish probable cause for arrest. However, because these tests can directly impact the outcome of a DWI case, it's essential to scrutinize them.
Prosecutors often rely heavily on breathalyzer results to prove intoxication, but experienced criminal defense attorneys know that these devices are not always accurate. That opens the door for various challenges that may weaken the state's case against you.
Common Ways to Challenge Breathalyzer Accuracy
There are numerous ways to attack the validity of a breath test result. Here are some of the most common and effective strategies:
The device wasn't properly calibrated: Breathalyzers need regular calibration to give accurate results. If the machine wasn't maintained or tested according to manufacturer guidelines or police department standards, the results may be unreliable.
The officer wasn't properly trained: Officers must be certified and trained to administer breathalyzer tests. If they skipped steps, misunderstood procedures, or made errors, those mistakes could taint the results.
The test was administered incorrectly: Breathalyzer tests must be conducted in a specific manner. For example, officers should observe the subject for a period (usually 15-20 minutes) before the test to make sure they haven’t burped, vomited, or eaten anything that could affect the reading.
Medical conditions influenced the result: Conditions like GERD (gastroesophageal reflux disease), diabetes, or certain diets can lead to falsely elevated BAC readings. A knowledgeable criminal defense attorney can bring this up during your case.
Environmental factors play a role: Chemicals in the air, residual mouth alcohol, or even certain products like mouthwash or breath fresheners can affect breath test readings. These outside influences might cast doubt on the reliability of the results.
Digging Into Device Maintenance Records
To challenge the breathalyzer, your attorney might look into its maintenance logs. These records can reveal whether the device was properly cared for or if there were past issues that might affect accuracy.
Some of the things an attorney will check include:
Calibration frequency: Devices must be calibrated on a regular schedule. If there’s no record of timely calibration, that could raise a red flag.
Repair history: A breathalyzer that’s been frequently repaired may have ongoing issues that compromise its reliability.
Manufacturer updates or recalls: If the machine model was subject to a recall or had software updates that were ignored, those could be valid grounds to question the test results.
Accessing and examining these logs could be key to building a strong criminal defense strategy in your Missouri DWI case.
Looking at the Officer's Actions
Even if the breathalyzer itself is in good working order, how the test is administered is just as important. Officers must follow proper procedures from start to finish. If your attorney finds errors or protocol violations, that could call the results into question.
Here are some procedural elements that could be challenged:
Failure to observe the required waiting period: Officers typically must observe the suspect for 15-20 minutes before the test. If they skipped this step, the results may be flawed.
No second test administered: Missouri law often requires multiple breath samples to confirm accuracy. A single test might not be sufficient to prove intoxication.
Improper documentation: Sloppy or incomplete paperwork could cast doubt on the officer’s professionalism and the test’s reliability.
By focusing on these actions, a criminal defense lawyer can highlight weaknesses in the prosecution's case.
Questioning the Science Behind the Test
Breathalyzer tests rely on scientific principles to estimate BAC, but the accuracy can vary. Many defense strategies look at the underlying science to question how reliable those results really are.
Potential scientific weaknesses include:
Assumption of a standard blood-to-breath ratio: Breathalyzers assume a fixed ratio between breath alcohol and blood alcohol, but this varies from person to person.
Margin of error: Like any measuring device, breathalyzers have a margin of error. If your BAC reading is close to 0.08%, that small margin could make a big difference.
Breathing patterns and lung capacity: Shallow or irregular breathing can affect test results. Some people naturally have smaller lung capacity, which can skew the results.
By challenging the scientific validity of the test, your attorney can argue that the evidence doesn’t prove guilt beyond a reasonable doubt. For more information about the accuracy of a breathalyzer test, contact Attorney Jeff Jarrett.
Presenting Alternative Explanations
Another angle to challenge breathalyzer accuracy is to offer plausible alternative explanations for a high BAC reading. This doesn’t necessarily mean disputing that alcohol was consumed, but rather suggesting that the test doesn’t reflect true impairment.
Some examples of alternative explanations include:
Mouth alcohol from recent use of mouthwash or cold medicine
Diabetes-related ketones that can mimic alcohol
Residual alcohol in the mouth from recent drinking
These explanations can create reasonable doubt about whether the breath test results truly indicate intoxication.
Exploring Constitutional and Legal Defenses
In addition to technical or scientific flaws, breathalyzer evidence can also be challenged on constitutional or procedural grounds. If your rights were violated at any point during the stop, testing, or arrest, that may be grounds to suppress the breathalyzer results or even have the case dismissed entirely.
Some common legal issues that can support your criminal defense include:
Lack of probable cause: If the officer didn't have a valid reason to stop you in the first place, any evidence collected afterward—including breath test results—could be inadmissible.
Unlawful arrest: Arresting someone without proper legal justification violates their rights and can lead to suppression of key evidence.
Improper reading of Miranda Rights: If you were questioned after your arrest without being properly advised of your rights, your statements—and possibly other evidence—could be excluded.
Denial of access to legal counsel: If you asked to speak to a lawyer and were denied that opportunity, this can be used to challenge how the investigation was handled.
By thoroughly reviewing the circumstances of your arrest, a criminal defense attorney can uncover these violations and use them to strengthen your case.
The Importance of Legal Representation
Successfully challenging a breathalyzer test in Missouri takes more than just pointing out potential flaws. It requires a thorough understanding of both legal procedures and the science behind these tests. That's why working with a criminal defense attorney who handles DWI cases is so important.
Your lawyer will know what records to request, what questions to ask, and how to present a strong argument in court. They’ll also be able to identify whether your rights were violated during the traffic stop or arrest, which could lead to suppressed evidence or even a dismissal.
Reach Out Today
Just because a breathalyzer test shows a BAC over the legal limit doesn’t mean you’re automatically guilty. There are many ways to challenge the accuracy of these tests, and a strong criminal defense can help you protect your rights.
I provide services in the Kansas City Metro area, including Lee’s Summit, Missouri, and Liberty, Missouri. I also serve clients in Overland Park, Kansas, and Lawrence, Kansas. Call me at Jeff Jarrett Law Office today.