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Are Pennsylvania BAC Breath Tests Reliable?

December 6, 2017 by Mike Worgul in Criminal Defense, DUI

This is the second of a four-part series of blogs covering the reliability of BAC tests commonly used by law enforcement officers in Pennsylvania.

When charged with a DUI in Pennsylvania, the results of a blood alcohol concentration (BAC) breath test can significantly impact your case. However, these results aren’t always foolproof.

In this blog, we’ll discuss the accuracy and reliability of breathalyzer BAC tests, a common type of chemical test in DUI cases. Future posts will cover BAC blood and urine tests.

If you’ve been tested after a DUI stop, consult an experienced Pittsburgh DUI attorney at Worgul, Sarna & Ness, Criminal Defense Attorneys, LLC to protect your rights. Call us today at (412) 281-2146 for a free consultation of your case.

What Is a BAC Breath Test in Pennsylvania?

A Blood Alcohol Concentration (BAC) breath test is a type of chemical test used to estimate the amount of alcohol in a person’s bloodstream based on their breath. In Pennsylvania, law enforcement often relies on these tests during DUI stops to determine if a driver’s BAC is above the legal limit of 0.08%. This test typically involves the individual blowing into a handheld device (PBT) in the field or a larger breathalyzer machine at the police station.

The device then calculates the BAC by analyzing alcohol levels in the exhaled breath, applying a standard formula known as the “partition ratio” to convert the breath alcohol content to an estimated BAC level. Although these breath tests are commonly used in DUI cases, the results can sometimes be inaccurate due to factors like equipment malfunctions, procedural errors, and personal traits unique to the individual.

Understanding BAC Breath Tests in Pennsylvania DUI Cases

BAC breath tests are the primary tool law enforcement uses to estimate a driver’s blood alcohol content. These tests may involve:

Preliminary Breath Tests (PBT)

The PBT is a portable device used in the field by police that provide quick BAC results. This kind of test is mainly used to establish grounds for further testing.

Station Breathalyzers

These larger devices are primarily at police stations and will provide BAC readings that are often used as evidence in court.

By blowing into the device, a test subject’s exhaled air is analyzed for alcohol traces. While the results are commonly admitted as evidence, questions around accuracy and reliability frequently arise.

How Reliable Are Breathalyzers in DUI Cases?

Breathalyzers calculate BAC by assuming an “average” partition ratio (or multiplier) of 2,100, based on Henry’s Law. This means they assume that the amount of alcohol in breath is 1/2100th of that in the same quantity of blood. However, this standard ratio doesn’t account for variations among individuals, which can lead to unreliable results.

Factors That Can Affect Breathalyzer Reliability

Although BAC breath tests are widely used in Pennsylvania, their accuracy and reliability can be compromised by multiple factors. Some of the factors that can affect the results of a breathalyzer test can include:

Variability in Personal Traits

Breathalyzer tests rely on a standard “partition ratio” that assumed everyone metabolizes alcohol similarly but people’s bodies process alcohol differently. Factors such as age, gender, weight, and metabolism can influence how alcohol is processed, potentially skewing the results of the test. An experienced DUI attorney may challenge this standard ratio if there are doubts about the accuracy of your specific reading.

Faulty or Poorly Maintained Equipment

Breathalyzer devices must be regularly calibrated to ensure accurate measurements. If a device has not been properly maintained or calibrated as per regulatory standards, it can produce inaccurate results. Issues such as battery problems, sensor malfunctions, or software errors may affect the device’s reliability. In some cases, calibration records and maintenance logs can be examined to identify potential issues with the machine used in your test.

Influence of Personal Health and Habits

Several other personal factors can create inaccurate BAC readings, including:

Recent use of mouthwash or breath fresheners
Elevated body temperature
A unique blood cell-to-plasma ratio
Certain dietary habits

Certain medical conditions, such as acid reflux, GERD (gastroesophageal reflux disease), and diabetes, can interfere with breathalyzer readings. Some prescription medications can also alter the body’s processing of alcohol or trigger chemical reactions that may interfere with breathalyzer accuracy.

Environmental Factors and Interfering Substances

Breathalyzer tests can be affected by the presence of substances in the environment or in the test subject’s mouth. For instance, using mouthwash, breath fresheners, or other alcohol-containing products shortly before testing can result in higher BAC readings. Additionally, if the person has recently smoked, consumed certain foods, or used other substances that linger in the mouth, these factors could interfere with test results.

Procedural Errors by Law Enforcement

A valid BAC breath test requires strict adherence to proper procedures. Pennsylvania law mandates that:

The subject must be observed for at least 20 minutes before the test to ensure they have not consumed anything that could impact the reading.
The device’s mouthpiece must be replaced between tests to prevent contamination. If these procedures are not followed, it can cast doubt on the validity of the test results. An attorney can investigate whether law enforcement followed protocol, and any lapses in procedure could be grounds for challenging the results.

Timing of the Breathalyzer Test

Alcohol absorption varies over time, meaning that BAC levels fluctuate. If there’s a delay between the DUI stop and the breathalyzer test, the results may not accurately reflect your BAC at the time you were driving.

Each of these factors demonstrates that BAC breath tests, while widely used, have significant limitations. Questioning the accuracy of the test results is often an essential part of building a strong DUI defense.

How a Pennsylvania DUI Attorney Can Help You Challenge BAC Breath Test Results

BAC breath tests are not always reliable, and your defense may benefit from questioning the results. A skilled DUI attorney can help examine whether law enforcement followed proper procedures, faulty equipment was used, and if any personal factors could have skewed the BAC readings. Your attorney will leverage these details to contest test accuracy and potentially weaken the prosecution’s case. By questioning those elements, an experienced DUI attorney will work to reduce or dismiss your DUI charges, minimizing potential penalties.

Let Worgul, Sarna & Ness Fight For You

BAC breath tests are not the most reliable form of testing to determine blood alcohol concentration. If you submitted to a breathalyzer test after a DUI stop, you may have strong grounds to fight against any DUI charges filed against you. At Worgul, Sarna & Ness, Criminal Defense Attorneys, LLC, we know how to challenge the results of your breathalyzer test with the goal of minimizing or eliminating the penalties you are facing.