When you are suspected of driving under the influence, your breathalyzer test results have a considerable impact on the outcome of your case. If your blood alcohol content (BAC) is above the legal limit for the charge you face, prosecutors hold a powerful piece of evidence to use against you to obtain the conviction they are seeking. Prosecutors will not look for defects or shortcomings from a breathalyzer test; that is up to you and your lawyer. Challenging breath test evidence is not only a wise move on your part, but it could also lead to having your case completely dismissed.

It is not uncommon for a driver who is suspected of a DUI to successfully pass 100 percent of the field sobriety tests they are asked to complete, only to be found guilty based on evidence from a breathalyzer. But breath tests are not foolproof, nor are they guaranteed to be reliable.

A competent DUI attorney is well aware of what's at stake for you and your loved ones when the results of a breath test appear to not be in your favor. They can aggressively dispute the validity of the evidence with various strategies that could lead to dismissal, especially if the results of the breath test are the sole conclusive evidence being used to convict you.

Below are a variety of common defense strategies DUI lawyers use to challenge breath test evidence that is critical to your case and may lead to your DUI case dismissed.

Issues With A Portable Breath Test (PBT)

A Portable Breath Test (PBT), also referred to as a preliminary breath test, is a small machine carried by law enforcement officers that they keep with them in their vehicle for stops involving DUI, DWI, or APC (Actual Physical Control) arrests. When a driver is suspected of being intoxicated, an officer will ask them to blow into the device to get a general BAC reading. They will record the number given and use it to determine if the driver is impaired.

These mobile testing devices are often not calibrated. They are only intended to be used as a preliminary indication of whether a driver is impaired from alcohol or drugs. The results of a PBT are not permitted in court, and questioning their validity is, in many cases, a worthwhile defense strategy worth pursuing.

Human Error

Occasionally, a law enforcement officer will perform a breath test and tell the suspect that their BAC fell below the legal limit and not being charged. The person then receives a summons in the mail telling them that they are being charged with a DUI. This can occur because the police officer who performed the test wrote down the wrong number in their documentation. In these cases, the number written down would be a factual error and considered illegal.

Failure To Maintain The Breathalyzer Device

Like any other machine, a breathalyzer testing device needs to be maintained in order to avoid mechanical breakdowns. Without regular and proper maintenance, the results from the device can be inaccurate. Appropriate maintenance includes:

• Checking the charge of the battery
• Performing tests that reveal mechanical errors
• Making sure that all operations that involve the reading functions are working properly

If it can be shown that the breathalyzer device had mechanical difficulty due to improper maintenance, any evidence collected through the use of that device may not be used against you in court.

Failed Observation Period

Law enforcement officers are legally required to carefully observe a suspect for 20 minutes prior to administering a breathalyzer test. This is to make sure that the person suspected of driving under the influence does not regurgitate, belch, consume something, or do anything that might affect the test’s accuracy. Failure to observe the suspect during this period is a breach of protocol which can keep the breath test evidence collected from being allowed.

False Readings

Breath tests can produce false readings when a suspected driver has used a substance or chemical that interferes with the results. Chemicals that can compromise the results of a breath test include:

• Asthma medications such as budesonide, albuterol, salmeterol, and similar medications. These medications stay in an individual's airway for a more extended period than other types of medicines after they have been inhaled.
• Over-the-counter medications that contain alcohol, such as Vick’s products, Nyquil, or even cough drops.
• Oral gels, such as those used to treat toothaches and canker sores, can contain a local anesthetic ingredient known as Anbesol.
• Breath Sprays and mouthwashes with high alcohol content, especially if they are used just prior to the administration of a breathalyzer test.

History Of Improper Calibration Or Malfunction

Law enforcement agencies are legally liable for keeping a recorded history of every breathalyzer device in their possession. They must routinely calibrate and maintain these devices at regular intervals. These records can reveal that a breathalyzer machine was either improperly calibrated or has a history of malfunctioning.

It is also the legal responsibility of a law enforcement agency to have trained personnel who know how to maintain and operate these devices. If the person in charge of calibration and maintenance was not adequately trained, readings from those devices might not be inaccurate and are therefore unreliable. Expert witnesses who are specialists in breath testing are sometimes called to prove that a device placed into evidence was not calibrated correctly.

The person conducting the test must know how to calibrate the device to ensure an accurate reading properly. If the same device used for your testing is placed into evidence, the court can inspect it to ensure that it is fit for accurately detecting blood alcohol levels. Similarly, the defense can call an expert specializing in breath tests to testify how the device was improperly calibrated.

Unlicensed Breathalyzer Operator

Anyone who operates a breathalyzer device must have a valid, unexpired license and be certified to do so through the U.S. Department of Transportation. Law enforcement officers who are not current on their license cannot administer a breathalyzer test. Officers who are certified must follow specific protocol or risk having evidence thrown out.

Failure To Record Simulator Solution Value

When a law enforcement agency tests a breathalyzer device, they must perform a simulator test. A simulator test measures the alcohol content in a simulator solution, an ethyl alcohol used to simulate a specific blood alcohol content. The content of alcohol used in the solution must fall within a range of plus or minus .01 percent per weight per volume in order for the device to be certified. This information must be recorded, and failure to do so prevents the use of evidence obtained from that device.

Inconsistent Range Of Breath Test Results

Once a police officer administers a breath test, they must wait for at least five minutes (and no more than ten minutes) before giving a second test. The results of the two BAC tests must fall within .02 percent of each in order to be considered accurate. If the two tests do not meet these criteria, the results are deemed "out of range," and their reliability and accuracy can be challenged.