Breath Test in Proper Working Order

Breath Test in Proper Working Order

Getting pulled over on suspicion of drunk driving is never a fun experience. The flashing lights in your rearview mirror make your heart race as you pull to the side of the road. An officer approaches your window and asks you to step out of the vehicle to perform some field sobriety tests. You do your best to follow the officer’s instructions as they have you walk heel-to-toe in a straight line and stand on one leg. But with your nerves rattled, you wobble a bit and put your foot down once or twice to steady yourself.

The officer determines you are impaired and places you under arrest for driving under the influence (DUI). You are transported to the police station where the officer reads you your rights and asks you to submit to a breath test to determine your blood alcohol content (BAC). This chemical test can make or break your DUI case, so it’s important to understand how breath tests work and what defenses there are if the results are inaccurate.

How Breath Tests Work

Breath tests, commonly referred to by the brand name Breathalyzer, don’t actually measure alcohol content directly. Instead, they estimate BAC indirectly by measuring the amount of alcohol in deep lung air. Devices like the Intoxilyzer 5000 use infrared spectroscopy to determine alcohol concentration. The machine shines an infrared light through the breath sample and measures how much light is absorbed. The more alcohol present, the more light will be absorbed.

The device then uses a partition ratio of 2100:1 to convert breath alcohol to estimated blood alcohol. This means it is assumed that the alcohol concentration in breath is 1/2100th of the concentration in blood. However, this partition ratio varies from person to person and even within an individual over time. Factors like body temperature, hematocrit levels, and breathing pattern can affect the ratio and lead to over- or under-estimation of BAC.

For a breath test result to be admissible in court, the prosecution must lay a proper foundation proving:

• The machine was in proper working order
• It was operated by a qualified individual
• Testing methods were properly followed
• The chemicals used were the proper kind and compounded in the proper proportions

If any one of these elements is lacking, the defense may be able to get the breath test results thrown out or prevent them from being admitted at all.

Proper Working Order

The most common way to challenge breath test results is by attacking the reliability of the machine itself. Breath testing devices must be properly maintained and calibrated regularly to ensure continued accuracy.

Maintenance procedures can include replacing filters, cleaning sensors, adjusting gas flow rates, and leak detection. Calibration involves testing the device’s responses using solutions of known alcohol concentrations. This determines if the machine is accurately measuring samples compared to the target values.

Police departments are required to keep logs documenting all maintenance and calibration checks performed on each device. Certificates of analysis for the simulator solutions used should also be available. Thoroughly reviewing these records can reveal gaps or deviations from protocol that call the reliability of the device into question.

For example, if a breath test was performed a month after the machine’s last calibration, this exceeds the 30-day calibration frequency requirement in many states. Or the logs may show the device was reading high or low during calibration checks, indicating it was not properly calibrated and would produce inaccurate results.

Mouth Alcohol

Mouth alcohol can also create falsely high breath test results. Alcohol residue can remain in the mouth from recent consumption of alcoholic beverages, regurgitation of stomach contents, dental work, or using mouthwash or breath spray.

Breath testing devices are supposed to measure alcohol from deep in the lungs, not the mouth cavity. But they cannot distinguish where the alcohol is coming from. Any alcohol lingering in the mouth will be picked up and affect results.

To prevent mouth alcohol issues, officers are trained to observe suspects for 15-20 minutes prior to testing to allow any residual mouth alcohol to dissipate. They are also supposed to take two separate breath samples at least two minutes apart, with the lower of the two being used as the final result.

If mouth alcohol is present, the first sample should be significantly higher than the second. Reviewing the officer’s report and observation video can reveal a lack of proper observation period or inconsistent samples, indicating a mouth alcohol problem.

Improper Administration

Even if the breath testing device is in working order, the officer must administer the test properly. Police are trained on how to operate the machine and run through a checklist of steps. Failing to adhere precisely to the procedures can render the results unreliable.

For example, the officer may not have observed the required deprivation and observation period prior to testing. Or they may have improperly entered data like the subject’s name or time of the test. The officer may have failed to perform the required blank tests before and after the actual breath test.

Reviewing the officer’s report against the breath test machine’s printout can uncover discrepancies that point to improper administration. Analysis of the observation video can also reveal mistakes in the testing sequence.

Radio Frequency Interference

Breath testing devices contain microprocessors that could be impacted by radio frequency interference (RFI). Radio waves from sources like police radios, cell phones, and police station equipment may affect the machine’s electronics and cause errors.

RFI can alter the test results, cause a malfunction, or even lock up the machine. Although breath test devices have RFI detectors, they are not always effective. The only way to know for sure is to review radio transmission logs from the time of the test to see if high levels of radio traffic coincided with the breath testing sequence.

Expert Witnesses

Given the technical nature of breath testing devices and procedures, using a knowledgeable expert witness to evaluate the machine’s maintenance records, calibration checks, printed results, and observation video is key. They can spot issues and flaws that a layperson would miss.

An expert can also provide crucial testimony about the partition ratio, how conditions like gastroesophageal reflux disease (GERD) and diabetes can impact results, the prevalence of RFI at police stations, and other factors that call breath test accuracy into question.

Defense lawyers have a wide range of strategies for attacking breath test results and preventing them from being used as evidence of intoxication. But the devil is in the details when it comes to spotting issues with maintenance, calibration, administration, and other testing elements. Thorough investigation and analysis by an experienced DUI attorney provides the best chance at getting unreliable or inaccurate breath tests thrown out.

Drivers should be aware of their legal right to refuse a roadside preliminary breath test during a traffic stop. While refusing comes with penalties to your driver’s license, it eliminates the chance of an erroneous roadside reading being used against you.

If you are placed under arrest and taken to the station for chemical testing, you have the choice between a breath test or blood draw. There are pros and cons to each option. With blood, you avoid the machine reliability issues of breath testing. However, if the blood is not drawn properly or makes its way through the crime lab untested for long periods, that creates its own areas of attack.

Don’t leave your fate to chance by relying on inaccurate breath or blood tests. Work with an experienced DUI lawyer to build the strongest defense against the charges. An attorney can leverage their expertise to attack chemical test results and win dismissal or acquittal of charges whenever possible. With so much at stake, it pays to have a knowledgeable professional fighting for your rights.