How Reliable Are Breathalyzer Tests?

You’ve been placed under arrest on suspicion of DUI. The officer’s next step, as it is in many DUI investigations, is to request that you submit to a test on a breathalyzer machine. If you do provide a breath sample for testing, the result of your test can determine whether you will face arrest and criminal charges.

In Nevada, DUI evidentiary breath tests are conducted on an Intoxilyzer 9000 or a similar machine. Police and prosecutors hold out these machines to be precise scientific instruments that accurately measure the amount of alcohol in a suspect’s system. However, the truth is these devices can be unreliable and might give accurate results.

How Do Breathalyzers Work?

A breathalyzer is an evidentiary breath-testing instrument that estimates the alcohol concentration in your system based on a sample of your deep lung air. Using a known quantity of breath, a breathalyzer emits an infrared light that is absorbed by alcohol molecules in the breath sample.

The machine measures the amount of infrared light absorbed and converts this measurement into an alcohol concentration reading. The final result is expressed in terms of grams of alcohol per 210 liters of breath.

Breathalyzers Are Unreliable Instruments

Despite technological advancements, a person’s alcohol concentration as measured by any breath-testing device can still vary from the person’s blood alcohol concentration. When your guilt or innocence is measured in hundredths of grams, even slight variations between these two figures can have serious consequences.

The level of variance in a breath test can depend not only on the machine but also on how well it is maintained. Machines that are not regularly serviced and certified cannot be trusted to provide accurate measurements. Nor can a device’s result be trusted if the breath sample is not collected under controlled conditions.

Top 4 Reasons Your Breath Test Result May Be Wrong

Suppose that you submitted to a breathalyzer test and were surprised by how high the result was. These are four circumstances that can lead to an erroneously high breathalyzer result.

1. Medical Conditions

Certain medical conditions, most notably uncontrolled diabetes, can cause a breathalyzer to return an incorrect result. This is due to the presence of ketones in the breath of someone whose blood sugar level is not well regulated. To a breathalyzer, these ketones appear to be alcohol molecules and are measured the same way.

2. Insufficient Sample

If you have ever provided a breath sample, you know that subjects are told to blow into the machine for an extended time. This aims to ensure that the machine measures air located deep within your lungs and not in your mouth. If you do not blow long enough, the machine may read any residual alcohol on your breath and give inaccurate results.

3. Environmental Contaminants

The automatic testing cycle a breathalyzer goes through includes a “purge.” During this step, the machine draws in air from the surrounding environment to clear out any residual alcohol that might be in the machine. It is akin to cleaning a plate before putting food on it so that you taste the meal and not whatever was on the plate previously.

However, if alcohol molecules are present in the air and the machine draws this air in, then the purge has failed its purpose and any resulting reading will be incorrect. While a breathalyzer is supposed to detect this situation and abort the remainder of the test, it does not always happen.

4. Breathing Patterns and Regurgitation

The way you breathe before submitting your breath sample can affect your test result, too. Hyperventilating, or breathing very quickly, can increase the amount of alcohol molecules the breath testing machine will detect. The breathalyzer cannot account for or adjust for hyperventilation, causing any resulting reading to be suspect.

Similarly, burping or throwing up just before giving a test can cause an abnormally high alcohol reading. In this situation, your stomach contents reenter your mouth and contaminate any deep air breath sample you might provide. For this reason, officers are supposed to stop breath testing if they notice you burp or regurgitate.

What to Do if Your Breath Sample Is Over the Legal Limit

If you choose to submit to a breath test on a breathalyzer machine, do not accept the results at face value. Before accepting any plea offer or admitting guilt, ask an experienced Nevada DUI attorney to examine the circumstances of your breath test. They might find a way to challenge the results and increase your chances of beating the charges.

If you are facing DUI charges in Nevada, contact the DUI Doctor for professional advice, assistance, and representation. Schedule a free consultation to discuss your options for resolving your case.