Breath Test Results Within Acceptable Tolerance

Breath Test Results Within Acceptable Tolerance

Breath tests are commonly used by law enforcement to determine blood alcohol concentration (BAC) levels during drunk driving investigations. However, even when done properly, these tests have a margin of error that must be taken into account. This article will examine what constitutes an acceptable margin of error for breath tests, legal defenses that may apply when test results are near the legal limit, and the implications for drunk driving cases.

How Breath Tests Work

Breath tests, commonly referred to as breathalyzers, estimate a person’s BAC by measuring the amount of alcohol in their breath. Most states set the legal BAC limit for driving at 0.08% or higher. When pulled over on suspicion of drunk driving, a driver will be asked to blow into the breath testing device for several seconds until an adequate sample is obtained. The device uses infrared spectroscopy to detect the presence of alcohol and estimate the BAC based on the breath sample[1].

While reasonably accurate, breath tests do have a margin of error usually around 0.01% BAC[2]. This means a driver with a 0.079% BAC could potentially blow a 0.089% on the breath test, putting them over the legal limit. Conversely, a driver at 0.081% might blow below the limit at 0.071%.

Acceptable Margin of Error

Most states allow a variance of up to 0.02% BAC between the actual BAC and the breath test results[3]. So if the legal limit is 0.08%, a breath test result between 0.078% and 0.082% would be acceptable and still considered valid evidence of being over the limit.

This accounts for the inherent margin of error in breath testing devices. As technology improves, many law enforcement agencies have adopted more advanced and accurate devices with margins of error closer to 0.005% BAC[4]. Still, the 0.02% variance is generally accepted nationwide as a reasonable tolerance.

Defenses for Borderline Results

When breath test results come back right at the legal limit, such as 0.08% or 0.081%, the inherent margin of error becomes very relevant. The closer the results are to that 0.08% threshold, the more arguable it is that the driver’s true BAC was actually below 0.08% [5].

In these borderline cases, the defense will scrutinize the accuracy of the specific device used and the qualifications of the operator who administered the test. Procedural errors by the officer, lack of maintenance records for the device, and other technicalities around how the test was performed can be grounds for challenging the validity of the results in court.

The defense may also request the driver’s blood be drawn shortly after the breath test and analyzed to verify the BAC. If the blood test comes back lower, it calls the breath test results into question. The timing of when the driver last drank alcohol becomes critical in these situations as well.

Implications for DUI Cases

While a 0.02% variance might not seem like much, those few hundredths can make all the difference for a driver near the 0.08% limit. Even if the breath test was done properly, results at 0.081% or 0.082% are reasonably disputable when factoring in the margin of error.

In these cases, the prosecution has the burden of proving beyond a reasonable doubt that the driver was over the legal limit at the time they were driving. Skillful DUI defense lawyers know how to leverage uncertainty around borderline breath test results to negotiate dismissals or reduced charges for their clients.

On the other hand, breath test results substantially over the legal limit, such as 0.15% BAC or higher, face fewer challenges. The inherent margin of error is less relevant the further past the legal limit the results are. Still, defenses should explore any procedural flaws and technicalities around the breath testing process when representing clients facing drunk driving charges.

Breath Testing During COVID-19

The COVID-19 pandemic has raised new issues around breath testing for law enforcement. There are concerns over virus transmission when drivers blow directly into the device mouthpiece. Some agencies now use sterile straws or have officers wear gloves when holding the devices.

However, any modifications to standard procedures could potentially be exploited by defense lawyers challenging the validity of breath tests performed during the pandemic. As courts resume more normal operations, they will likely see an uptick in drunk driving cases involving debates over COVID-era breath testing protocols.

When to Refuse a Breath Test

Drivers pulled over on suspicion of DUI often wonder if they should refuse the breath test. While each case is unique, there are some general guidelines to consider:

• If you’re confident you are under the legal limit, taking the test will provide proof. However, the margin of error means even if you are under 0.08% BAC, the results could show over.
• If you know you are likely over the limit, refusing the test prevents prosecutors having that hard evidence. However, test refusal usually leads to stiff penalties like automatic license suspension.
• For borderline cases near the legal limit, test refusal may be wise to avoid results that could go either way due to the margin of error.

Of course, these decisions should be made after consulting with a DUI lawyer whenever possible. Never admit guilt or agree to field sobriety tests during a traffic stop.

Using Margin of Error in Your Defense

Don’t assume you have no defense just because your breath test results came back over the legal limit. Digging into that inherent 0.02% margin of error provides opportunities to fight the charges and protect your rights.

With an experienced DUI defense attorney negotiating for you, a breath test result of 0.081% or 0.082% does not automatically lead to a conviction like some drivers fear. Prosecutors know juries demand solid proof beyond a reasonable doubt. Leverage the margin of error to place doubt on borderline results.

While breath tests can provide valuable evidence, their limitations must be factored in when determining guilt and upholding justice. Understanding acceptable margins of error allows drivers, attorneys, judges, and juries to make informed decisions in DUI cases. Carefully scrutinizing results near the legal limit is key for balancing public safety with the rights of the accused.