The science behind breathalyzer and blood tests is not flawless. These devices and procedures are susceptible to a host of errors, from calibration and maintenance issues to human error and physiological factors. A successful DUI defense strategy involves challenging the reliability of this evidence by scrutinizing the traffic stop, the test, the administration, and the science of the process.
Key Takeaways:
- Breathalyzer results can be challenged due to a variety of factors, including improper calibration, operator error, or the presence of “mouth alcohol” from sources like mouthwash or medical conditions.
- Blood test results are also susceptible to errors. These can include a flawed chain of custody, improper sample collection by a phlebotomist, or mistakes made during laboratory analysis.
- A key part of defending against a DUI charge is to undermine the reliability of the chemical test results. An experienced attorney can achieve this by scrutinizing every detail of the test’s administration, the device’s maintenance records, and the handling of the evidence.
Facing a DUI charge in Illinois or Missouri is a daunting experience, and the state’s case often hinges on one key piece of evidence: your blood alcohol concentration (BAC). A breathalyzer or blood test result can seem like a smoking gun, leading many to believe that a conviction is inevitable. However, the science behind these tests is not infallible.
A skilled defense attorney knows that these devices and procedures are subject to a host of flaws – from calibration errors to physiological factors – that can render the results unreliable. Understanding these potential weaknesses is the first step toward building a strong defense.
How A Breathalyzer Works (and Where It Can Go Wrong)
A breathalyzer is designed to measure the amount of alcohol in the air you exhale, which is then used to estimate the concentration of alcohol in your blood. The device operates on the principle that the concentration of alcohol in your breath is directly proportional to the concentration in your blood. The machine uses a chemical reaction or infrared light to detect and quantify the alcohol molecules in your deep lung air.
However, this process relies on some assumptions that are often not true in the real world. Here are some of the most common issues that can lead to an inaccurate breathalyzer reading:
- Calibration and Maintenance Errors: Breathalyzers are sophisticated instruments that require regular calibration and maintenance to remain accurate. In Illinois, devices must be calibrated at least every 62 days. If a device has not been properly calibrated or if the maintenance records are incomplete, the results can be challenged. An attorney can subpoena these records to expose a lack of proper upkeep.
- Operator Error: The officer administering the test must be trained and certified. Furthermore, they must follow specific protocols. For example, in Illinois, the officer is required to observe the suspect for a continuous 20-minute period before administering the test. This is to ensure the subject does not eat, drink, burp, or vomit, as these actions can introduce “mouth alcohol” that skews the reading. If the officer fails to follow this crucial step, the test results may be invalidated.
- Mouth Alcohol vs. Deep Lung Alcohol: Breathalyzers are supposed to measure alcohol from your deep lungs, but they can’t always distinguish this from residual alcohol in your mouth. This “mouth alcohol” can come from several sources, including:
- Recent consumption of alcohol.
- Using mouthwash or breath spray.
- Dental work or dentures that can trap alcohol.
- Medical conditions like acid reflux, GERD, or heartburn can bring stomach contents (and alcohol) back up into the mouth.
- Physiological and Medical Factors: Certain medical conditions and even your unique physiology can produce a false positive on a breathalyzer. For example, individuals on a ketogenic diet or those with diabetes may have high levels of acetone on their breath. The breathalyzer may mistake this acetone for alcohol, leading to an artificially high BAC reading.
Challenging the Accuracy of a Blood Test
While a blood test is often considered more accurate than a breathalyzer, it is by no means foolproof. The process, from collection to analysis, involves a chain of custody with multiple points where errors can occur. Challenging a blood test often involves scrutinizing the following key areas:
- The Chain of Custody: This is a crucial legal principle that requires the prosecution to prove that the blood sample was handled properly at every stage. An unbroken chain of custody ensures the sample was not tampered with, contaminated, or mixed up with another person’s sample. A defense attorney will investigate:
- Who drew the blood, and if they were a licensed medical professional.
- Whether the vial was properly labeled and sealed.
- How the sample was stored and transported. Was it refrigerated to prevent fermentation?
- Whether there are any unaccounted-for gaps in the documentation of who had possession of the sample.
- Improper Phlebotomy Procedures: The person who drew your blood must follow strict medical procedures. For example, using an alcohol swab to clean the skin before the draw can contaminate the sample, leading to a falsely elevated BAC reading. Additionally, the blood must be drawn into a vial that contains an anticoagulant and a preservative to prevent the sample from clotting and to stop fermentation, which can naturally increase the alcohol content over time.
- Laboratory Errors: The blood sample is eventually sent to a lab for analysis, where it is tested using a process called gas chromatography. This is a complex scientific procedure, and human error can occur. An attorney can challenge the lab’s methodology, the technician’s qualifications, and the accuracy of the equipment.
Building Your Defense: It’s All About the Details
When a DUI case hinges on a chemical test, a successful defense strategy is built on challenging the reliability of that evidence. This is where an experienced attorney’s knowledge of the science and the law becomes invaluable.
A good defense attorney won’t just accept the state’s evidence at face value. They will:
- Scrutinize the Police Report: Review the officer’s report for any procedural errors, such as failing to observe the 20-minute waiting period before a breathalyzer test.
- Subpoena Maintenance Records: Demand the maintenance and calibration logs for the breathalyzer device used in your case.
- Question the Evidence: Look for breaks in the chain of custody for a blood sample or evidence of improper collection procedures.
- Consult Expert Witnesses: An attorney may hire an expert toxicologist or chemist to testify about the scientific flaws in the testing process and the potential for inaccurate results.
- Investigate Physiological Factors: Review your medical history to determine if a condition such as GERD or diabetes may have influenced the test results.
Ultimately, by casting doubt on the accuracy of the breathalyzer or blood test, an attorney can undermine the foundation of the prosecution’s case and open the door to a more favorable outcome.
Don’t let a faulty test result destroy your future. At Michael Reid Legal Solutions, we provide elite DUI defense and use our litigation experience to identify and expose the scientific and procedural flaws in the state’s evidence. We are not afraid to challenge a breathalyzer or blood test to protect your rights!
If you have been charged with a DUI in Illinois or Missouri, contact us for a complimentary strategy session. We’re here to help you understand your options and fight for the best possible outcome.