Challenging the Results of a DUI Breath Test
Breath test results are usually the most important pieces of evidence in drunk driving cases. When the results of a breath test reveal that a motorist charged with driving under the influence was operating their vehicle with a blood alcohol concentration of 0.08% or higher, the prosecutor assigned to the case may confidently believe that they have sufficient evidence to secure a conviction. This confidence is well founded most of the time, but there are situations where the validity of a breath test or the accuracy of breath test results could be challenged.
What Is a Breath Test?
When people consume beer, wine or liquor, the alcohol they ingest passes from the stomach into the bloodstream. Once in the blood, alcohol travels to all parts of the body, including the lungs. This means that the amount of alcohol found in a motorist’s breath can reveal how much alcohol is in their blood. Breath tests are conducted in the following way:
- The test subject blows into a tube connected to a breath-testing device for several seconds.
- The exhaled air enters a testing chamber containing potassium dichromate and other chemicals.
- If alcohol is present in the breath sample, the color of the chemical solution changes from red to green.
- A photocell sensor measures the degree of color change and produces an electrical current.
- The electrical current is converted into a numerical BAC value.
People who are arrested for DUI usually take two breath tests. They are tested at the roadside using portable devices that police officers keep in their vehicles, and they are tested again at a police facility during the booking and processing procedure. The second test is conducted using more sophisticated equipment, and it is these results that are used in court.
Refusing a Breath Test
Drivers who are facing drunk driving charges may think that refusing to take a breath test will deprive the prosecutor assigned to their case of crucial evidence and make proving guilt beyond reasonable doubt difficult or impossible. This is not a good idea. Every state has an implied consent law, which means motorists who refuse to take chemical tests to determine whether or not they are intoxicated commit an offense.
People agree to provide blood or breath samples to police officers as a part of their driver’s license applications. Police officers can only request a chemical test when they have good reason to believe that a driver is impaired. Signs of intoxication that could justify such a request include slurred speech, unsteadiness, watery or bloodshot eyes and the odor of alcohol. Refusing a breath test in these circumstances will lead to penalties, even if DUI charges are dismissed. In Pennsylvania, the penalties for refusing a chemical test are:
- First offense: Motorists who refuse to take a chemical test for the first time are banned from driving for 12 months and must pay up to $500 to have their driving privileges restored.
- Second offense: The driver’s license suspension is increased to 18 months, and the restoration fee can be as high as $1,000 after a second chemical test refusal.
- Third offense: The cost of restoring driving privileges increases to up to $2,000 for drivers who refuse to provide a breath or blood sample for a third time.
This means that refusing to submit to a chemical test in Pennsylvania will have similar consequences to a DUI conviction, and it may not even prevent a criminal prosecution. The refusal could provide grounds to obtain a search warrant to conduct a blood draw, and the testimony of a police officer along with the refusal may be enough to secure a DUI conviction even if blood is not drawn. Consenting to a breath test and then challenging the results may be a more prudent approach. This can be done in several ways.
Challenging the Validity of a Traffic Stop
The vast majority of DUI cases begin with a traffic stop. Drivers are protected by the U.S. Constitution when they are behind the wheel, which means police officers cannot initiate traffic stops unless they have reasonable suspicion to believe that a crime has been committed, is being committed or is about to be committed. The courts have ruled that police officers have grounds to pull a vehicle over when they:
- Observe a moving violation like speeding, running a red light or making an illegal lane change
- Notice signs of impairment like weaving between lanes
- See equipment violations like windows that are tinted too darkly or broken lights
- Receive a report about a suspected drunk driver that includes a vehicle description
- Observe an expired registration
If a police officer pulls a vehicle over without the requisite reasonable suspicion, the traffic stop could be ruled illegal. In these situations, all evidence gathered during the illegal traffic stop will be excluded under the fruit of the poisonous tree doctrine. This includes the observations of the police officer and the results of any chemical tests. This happens rarely because police officers know that their actions are scrutinized closely. When a police officer suspects that a motorist is impaired, they will usually wait until they observe a violation of some kind before they switch on their lights and siren.
Challenging the Test Procedure
Police officers must follow a strict procedure when they administer breath tests. If they deviate from this procedure, breath test results could be unreliable and subject to challenge. A breath test should not be conducted until at least 15 minutes have passed since the suspect last consumed alcohol. This is because traces of alcohol in the mouth could influence the result. Smoking, mouthwashes or other products that contain alcohol and medical conditions including diabetes and gastroesophageal reflux disease can also skew BAC readings. This is why an experienced Pennsylvania criminal defense attorney will ask clients charged with DUI a lot of questions about their medical histories and how and when their breath was tested.
Questioning the Accuracy of the Testing Equipment
The breath-testing devices used by law enforcement are extremely sophisticated and accurate, but they only produce reliable results if they are maintained properly and recalibrated regularly. That does not always happen. Improper calibration can lead to BAC readings that are 40% too high, which is why judges in New Jersey and Massachusetts invalidated the results of 30,000 breath tests in 2019 alone. When journalists investigated breath-testing procedures in the United States, they discovered:
- A breath-testing machine that was being used as a nesting site by rats
- Police departments using chemical solutions that had been made in-house
- Breath-testing machines with numerous software errors in their programming
Police departments are expected to keep accurate records when they maintain and recalibrate their breath-testing equipment, and test results may be challenged when these records are missing or incomplete.
Establishing Reasonable Doubt in Drunk Driving Cases
If you are charged with driving under the influence, you deserve the best defense possible. The attorneys at Bauer, Scanlon & Wigginton have decades of criminal defense experience, and they will advocate fiercely on your behalf. If you would like to discuss your legal options with one of our Pennsylvania criminal defense attorneys, you can schedule a consultation at our Media office by calling (610) 590-5092 or filling out our online form.