Criminal Defense Lawyer Norfolk, VA and throughout Hampton Roads
Criminal Defense Lawyer Norfolk, VA and throughout Hampton Roads

How a DUI Attorney Can Challenge Breathalyzer Test Results

Glass of whiskey, car key, and handcuffs on a table.

The right defense lawyer can push back on the evidence against you.

If you've been charged with driving under the influence (DUI), one of the most important pieces of evidence in your case is the breath or blood test results. Without those results, it's much more difficult for the prosecution to prove beyond a reasonable doubt that you were under the influence of alcohol. As such, one way to fight a DUI charge is to challenge the breath or blood test.

There are many ways an experienced DUI attorney can challenge your breathalyzer test results. In general, those strategies fall into two categories: challenging the legal process that led up to the breath or blood test and challenging the test itself.

Challenging the legal process that led to the breathalyzer

The police have to follow certain rules throughout a DUI investigation and arrest. If they violated your constitutional rights at any point in the process, it may be possible to throw out the evidence they found subsequent to the violation, including the breathalyzer results.

In order to pull you over for DUI in the first place, the police need reasonable suspicion that a violation has occurred; that is, an actual, articulable reason that isn't just a hunch. Some types of driving behavior that typically qualify as reasonable suspicion are speeding, weaving between lanes, and disobeying traffic signs and signals. Other types of driving behavior, such as driving slowly or weaving within a lane, are typically not enough to establish reasonable suspicion.

In order to arrest you for DUI, the police need probable cause to believe you were impaired while operating a vehicle. Driving behavior can help to establish probable cause, as can your demeanor and appearance during the traffic stop. Field sobriety tests (FST) and the preliminary breath test (PBT) given at the scene can also help to establish probable cause. Evidence discovered in your vehicle, such as an open container of alcohol, can also establish probable cause to arrest you — but the police also need probable cause to suspect evidence of a crime may be found before they can search your vehicle without your consent.

Virginia's implied consent law can also come into play when challenging breath test results. The law applies if you were operating a motor vehicle on a public highway and arrested for DUI or a similar offense within 3 hours of operating the vehicle. An attorney may be able to question whether you really were operating a motor vehicle or really were on a public highway, depending on the circumstances of the arrest.

If the police violated your legal rights prior to the breathalyzer test, then the test results and anything else they discovered after the violation may be inadmissible in court. Often, this means there is not enough evidence left for a conviction and the DUI charge will be dropped or dismissed.

Challenging the breath or blood test itself

Even if the police did everything right leading up to the test, they have to follow the rules when conducting the test itself. There are several reasons an attorney can question the results of a DUI breath or blood test, including:

  • False positives: A breath test doesn't just detect alcohol; it detects any substance in the "methyl group." Certain medical conditions, such as diabetes, can produce other chemicals that the breath test cannot distinguish from alcohol. Smoking can also affect your breath test results, as can various activities that involve industrial chemicals such as painting and siphoning gas.
  • Improperly calibrated machines: Like any measuring device, breathalyzers need to be calibrated to produce an accurate result. If the police can't prove that the breath test machine was properly calibrated, your attorney can call the results into question.
  • Chain of custody: If your DUI charge is based on a blood test rather than a breath test, then the chain of custody of the blood sample is critical. If the police cannot account for the entire chain of custody, the results can be thrown out.

In short, breathalyzer tests aren't perfect, and neither are the police officers who conduct them. Humans make mistakes, and machines fail. The right attorney can thoroughly investigate the situation and identify evidence that can help you fight back.

If you've been charged with DUI, get a defense attorney with trial experience

While the breathalyzer results are a key piece of evidence in a DUI case, they are just one aspect of the case. When you're facing charges that can derail your future, you need a lawyer who will put in the time and effort to thoroughly review the entire situation and come up with a legal strategy to protect your rights. You need the Norfolk DUI defense attorneys at Welch & Wright, PLLC.

If you are facing DUI charges in Norfolk, Newport News, Hampton, Virginia Beach, or anywhere in the Hampton Roads region, take immediate action. Contact us today for a free, confidential consultation.

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