DUI Defense: The Hidden Truth About Breathalyzer Accuracy

Drivers face serious charges when police use breathalyzers to measure blood alcohol content (BAC). Many people trust these devices completely. However, the science behind these tests has significant flaws a strong legal defense can explore. Understanding these weaknesses is key to protecting your rights against a driving under the influence (DUI) arrest.

Other compounds create false positives

Breathalyzers use infrared light to detect alcohol, but they cannot distinguish between ethanol (drinking alcohol) and other compounds. Many products, like mouthwash or certain medical conditions, cause similar molecules to appear in the breath. This non-specific technology mistakenly identifies these other substances as alcohol, causing a reading that is higher than the driver’s actual BAC.

Temperature changes skew results

The temperature of the subject’s breath significantly impacts the test’s accuracy. A higher body temperature causes more alcohol to vaporize into the breath. For instance, people with a fever or those who exercise vigorously immediately before the test will yield higher, inaccurate BAC readings. Police officers rarely take an individual's temperature before administering the test.

Failure to observe the subject

Alabama law requires officers to observe the subject for a minimum of 20 minutes before the test. This observation period ensures the subject does not belch vomit or place anything in their mouth. Residual mouth alcohol from burping or chewing gum drastically inflates the BAC reading, sometimes by 100% or more. If an officer fails to strictly follow this required observation protocol, the test results become unreliable.

Seeking legal support

These scientific gaps provide crucial opportunities for defense attorneys. Attorneys challenge the admissibility of the test results by highlighting the device’s technical limitations and the officer’s procedural errors. Anyone facing DUI charges may want to seek help from a legal professional. They demonstrate that the breathalyzer evidence is simply not reliable enough to prove guilt beyond a reasonable doubt. They can also properly investigate and present these complicated scientific arguments to the court.