October 26, 2026
How to Challenge Breathalyzer Results in Maryland
A breath test number can feel like the entire case has already been decided. It has not. Knowing how to challenge breathalyzer results starts with understanding that a reported blood alcohol concentration is evidence, not a verdict. The traffic stop, the officer’s observations, the testing process, and the machine’s records can all matter in a Maryland DUI or DWI case.
A successful challenge is rarely about finding one dramatic mistake. More often, it comes from carefully reviewing the details that led to the result and asking whether the State can prove the test was reliable and lawfully obtained. That review should begin quickly, because a DUI arrest can involve both a criminal court case and time-sensitive Motor Vehicle Administration consequences.
How to Challenge Breathalyzer Results in Maryland
In Maryland, police may ask a driver to take a breath test after an arrest for suspected impaired driving. The result may be used by the State, but it can be challenged. The right approach depends on the facts of the stop and the evidence available.
A defense attorney may examine whether the officer had a lawful basis to stop your vehicle, whether there was probable cause for the arrest, whether required advisements were properly given, and whether testing procedures were followed. If a legal violation occurred, the result may be limited or excluded. Even when the result is admitted, weaknesses in the testing process can affect how much weight a judge or jury gives it.
Do not assume that a high number means there is no defense, or that a lower number automatically ends the case. Maryland DUI and DWI allegations can involve several kinds of evidence, including driving behavior, field sobriety exercises, officer observations, body-camera footage, and breath or blood testing. Each piece should be reviewed in context.
Start With the Traffic Stop and Arrest
A breath test usually comes after a traffic stop, and the legality of that stop matters. Police generally need a valid reason to pull a driver over, such as an observed traffic violation, equipment issue, or reasonable suspicion of impaired driving. A vague hunch is not enough.
The next question is whether the officer had sufficient grounds to continue the investigation and make an arrest. Officers often point to factors such as an odor of alcohol, red eyes, speech, balance, or performance on roadside tests. Those observations can be subjective. Fatigue, allergies, anxiety, medical conditions, uneven pavement, footwear, weather, and simple nervousness may offer different explanations.
Video evidence can be especially useful here. A written police report may say a driver was unsteady or confused, while body-camera or dashboard footage may show a more complete picture. The report, video, dispatch records, and testimony should be compared rather than treated as interchangeable.
Question Whether the Breath Test Was Properly Administered
Breath-testing equipment is designed to measure alcohol in a breath sample and estimate alcohol concentration. It is not immune to human error or physical limitations. Officers must follow required procedures, and a departure from those procedures may create a meaningful issue in the case.
One key area is the observation period before testing. The purpose is generally to help ensure that the person does not eat, drink, smoke, vomit, burp, or place anything in their mouth that could affect the sample. Mouth alcohol can lead to a reading that does not accurately reflect alcohol in the bloodstream. The precise facts matter: Was the driver actually observed? For how long? Did the officer document interruptions or possible contamination?
Medical conditions may also be relevant. Gastroesophageal reflux disease, acid reflux, diabetes, certain diets, oral health issues, and some medications can affect the testing process or raise questions that deserve expert review. A medical condition is not an automatic defense, but it should not be dismissed without examining the person’s history and the test records.
The officer’s training and compliance with protocol may also be at issue. A test operator must use the instrument according to approved procedures. Missing paperwork, inconsistent documentation, or testimony that conflicts with video footage can all affect the reliability of the result.
Review the Machine’s Maintenance and Calibration Records
A breath-testing machine must be properly maintained, inspected, and calibrated. Like any measurement device, it is only useful when it is functioning correctly and when its performance can be documented.
A careful defense review may seek records relating to the specific instrument used, including inspection history, calibration checks, repair records, error logs, and records of prior tests. These documents can show whether the machine was operating within required standards or whether it had a history that calls the reading into question.
This does not mean every maintenance entry defeats a case. Some records reflect routine service with no effect on accuracy. But a documented malfunction, overdue inspection, unexplained error, or lack of supporting records may give the defense a real basis to challenge the State’s evidence.
Timing can matter as well. Breath alcohol levels change over time. If there was a significant delay between driving and testing, the test result may not neatly establish what the person’s alcohol level was at the time they were behind the wheel. The State may try to account for that delay; the defense can examine whether its assumptions are supported.
Understand the Difference Between Refusing and Challenging a Test
Some people believe refusing a breath test prevents the State from having evidence. That is not necessarily true. Police may still rely on driving behavior, officer observations, field sobriety testing, statements, and other evidence. In Maryland, refusing a test can also lead to separate license consequences through the MVA.
On the other hand, taking a test does not mean you have waived every defense. You may still challenge the stop, arrest, advisements, administration of the test, and reliability of the reported number. The best strategy depends on the specific situation, including whether there was a test result, a refusal allegation, an accident, prior alcohol-related driving history, or a commercial driver’s license.
If you received paperwork after an arrest, read it closely and keep it with your other documents. Administrative deadlines can be short. Missing an MVA hearing deadline may affect your ability to contest a suspension, even while the criminal case continues.
Preserve Evidence Before It Disappears
The most useful evidence is often available only for a limited time. Save the citation, charging documents, release paperwork, vehicle tow information, and any MVA notices. Write down what you remember while the sequence is fresh: where you were stopped, what the officer said, whether you were read rights or advisements, what happened before the test, and who was present.
It can also help to identify potential video sources quickly. Nearby businesses, residences, parking lots, and traffic cameras may have captured portions of the stop, though many systems overwrite footage within days or weeks. A lawyer can pursue available discovery and take appropriate steps to request or preserve evidence.
Avoid posting about the incident on social media. Comments made in frustration, even when intended for friends, can be misunderstood or used against you. Keep discussions limited to your attorney and the people who need to know.
Build a Defense Around the Whole Case
The strongest defense is not always an attack on the breath machine alone. A case may involve a combination of issues: an unjustified stop, weak signs of impairment, flawed field testing, an incomplete observation period, unreliable documentation, and a breath result that does not match the rest of the evidence.
There are also times when the records show that the test was administered correctly and the State has substantial supporting evidence. In that situation, practical counsel means having a clear conversation about options, risks, possible negotiations, and the steps that may help protect your license, work, and future. Every case deserves an honest assessment rather than false promises.
If you are facing a Maryland DUI or DWI charge, act before paperwork and deadlines begin to work against you. Montero Law Group can help you understand what happened, review the evidence, and make informed decisions at a stressful time. A breath test result may be a serious part of the case, but it should never be the only part of the story.