Can I Prove the Breathalyzer Was Wrong in a Maryland DUI Case?

 Posted on July 08, 2026 in DUI / DWI

You can challenge a breathalyzer result in a Maryland DUI case, and doing so is one of the most effective ways to fight the charge. It’s a common misconception that a breath test result is solid proof that cannot be questioned. However, breathalyzer devices can produce inaccurate readings for several reasons. You have options for challenging those results in court. If you are facing a DUI charge in 2026, a Harford County, MD criminal defense lawyer can examine the evidence and find out whether the result in your case can be challenged.

Does Maryland Law Set Requirements for Breath Testing?

Under Maryland Transportation Article Section 16-205.1 and Maryland State Police regulations, breath testing in DUI cases has to follow specific procedures. Any deviation from these requirements is a potential basis for challenging the result.

At Baltimore Legal Services, we will request all documentation related to the breath test. That includes maintenance and calibration logs, the officer's certification records, and any records of the observation period. These documents often reveal problems that are not obvious from the police report alone.

What Are the Most Common Reasons a Breathalyzer Can Give a False Reading?

There are several well-documented reasons why a breathalyzer can produce an inaccurate result. We will look at all of them when reviewing your case.

The Device Was Not Properly Calibrated

Breathalyzer devices have to be calibrated on a regular schedule to make sure they are giving accurate results. If the device used in your case was not calibrated within the required timeframe or was not calibrated correctly, the results may not be reliable. We can request the calibration records for that specific device and look for any gaps or problems.

The Officer Was Not Properly Certified

The officer who gives a breath test has to be trained and certified to use the specific device involved. If the officer in your case did not have the proper certification or if it had lapsed, the test results may not be admissible. We will check the officer's credentials as part of the investigation into your case.

The Required Observation Period Was Not Followed

Before giving a breath test, Maryland law requires the officer to watch the subject continuously for a set period of time, typically 20 minutes. This makes sure the person does not eat, drink, smoke, burp, or regurgitate before the test, all of which can affect the reading. If the officer did not follow this requirement, the test result can be challenged.

Medical Conditions Affected the Reading

Certain medical conditions can cause a breathalyzer to read higher than your actual BAC. For example:

• Acid reflux and GERD can push stomach alcohol into the mouth and throat, which the device picks up as a higher reading.
• Diabetes can cause the body to produce acetone, which some devices mistakenly read as alcohol.
• A low-carbohydrate diet can produce similar compounds.

If you have any of these conditions, we can look into whether they affected your result.

Residual Mouth Alcohol Existed

If you recently used mouthwash, took certain medications, or had a small amount of alcohol shortly before the test, leftover alcohol in your mouth can cause the device to read higher than your actual blood alcohol level. The required observation period is meant to prevent this, but if it was not properly followed, residual mouth alcohol becomes a real challenge to the result.

The Device Had a History of Malfunctions

Some breathalyzer devices have documented records of giving inaccurate results. Maintenance logs and repair records can show whether the device in your case had prior problems that were not properly fixed. If the device was known to malfunction and those issues were not corrected, that is important evidence that the result may not be reliable.

Schedule a Free Consultation With Our Northern Baltimore County DUI Defense Attorney

Challenging a breathalyzer result takes a detailed understanding of how these devices work and what the law requires. You need someone with the experience and dedication to dig into every part of the evidence and advocate for your rights aggressively. Attorney Brendan O'Brien has helped over 10,000 clients through serious criminal charges and brings more than 15 years of experience to every case. At Baltimore Legal Services, we offer custom flat fees so you know exactly what representation will cost from the start with no surprises.

Contact us at 858-523-8423 to schedule a free consultation with our Harford County, MD criminal defense lawyer today. We are available 24/7.