When facing a DUI charge in Maryland, evidence often determines whether your case is dismissed, reduced, or results in a conviction. Law enforcement relies heavily on tools such as breathalyzer tests, field sobriety assessments, and dash cam footage to substantiate DUI allegations. While these pieces of evidence may seem straightforward, they are not infallible.
Many drivers are unaware that errors in testing procedures, equipment malfunctions, or even environmental factors can compromise the accuracy of DUI evidence. Understanding the types of evidence, their limitations, and strategies for challenging them is critical for anyone navigating the Maryland legal system.
In this blog, we’ll break down the different types of DUI evidence, explain common pitfalls, and show how a Maryland DUI attorney can protect your rights.
Types of Evidence in DUI Cases
1. Breath Tests
Breath tests are one of the most common tools used to measure Blood Alcohol Concentration (BAC). In Maryland, there are two primary types:
A. Preliminary Breath Test (PBT)
- Conducted roadside using portable devices
- Provides a rough estimate of BAC
- Results typically cannot be used as direct evidence in court but establish probable cause for arrest
B. Evidentiary Breath Test
- Conducted at the police station with more sophisticated machines (Intoxilyzer 9000, etc.)
- Results are admissible in court and can heavily influence the outcome of the case
Common Issues With Breath Tests:
- Equipment calibration errors
- Improper administration of the test
- Residual mouth alcohol from recent food, medication, or mouthwash
- Health conditions such as diabetes, acid reflux, or respiratory disorders
Example:
In one Maryland case, a defendant’s BAC reading was challenged because the machine had not been calibrated according to state standards for over two weeks. The evidence was subsequently excluded, significantly weakening the prosecution’s case.
2. Field Sobriety Tests
Field Sobriety Tests (FSTs) are standardized assessments designed to evaluate a driver’s coordination, balance, and cognitive function. Maryland officers typically use the three tests recommended by the National Highway Traffic Safety Administration (NHTSA):
- Horizontal Gaze Nystagmus (HGN): Observes involuntary eye movements when following a moving object
- Walk-and-Turn: Measures the ability to maintain balance and follow instructions while walking in a straight line
- One-Leg Stand: Tests balance and ability to maintain posture on one leg
Potential Errors:
- Poorly lit or uneven road surfaces
- Fatigue, nervousness, or medical conditions impacting performance
- Improper instructions or bias from the officer administering the test
Case Example:
A Maryland driver successfully contested FST results after showing that a minor ankle injury affected performance, and the officer failed to consider this during the arrest.
3. Dash Cam and Body Cam Footage
Dash cams and body cams are increasingly common in Maryland law enforcement. Footage can serve as either a support tool for the officer’s account or as a method to identify procedural errors.
How Dash Cam Footage Can Affect a Case:
- Confirms or contradicts officer testimony
- Reveals improper traffic stops or breaches of constitutional rights
- Demonstrates discrepancies in breath test or FST administration
Example:
In Baltimore, dash cam footage revealed that an officer instructed a driver improperly during a walk-and-turn test, leading to the suppression of the FST results in court.
Challenges to DUI Evidence
Chain of Custody Errors
- Evidence must be tracked from collection to courtroom presentation
- Breaks in the chain can render breathalyzer results inadmissible
Equipment Malfunction or Improper Calibration
- Police equipment must meet state regulatory standards
- Regular maintenance and calibration logs are required by law
Officer Misconduct or Errors
- Procedural errors, such as failing to inform a suspect of their rights
- Improper administration of sobriety tests
- Bias or misconduct can be grounds to suppress evidence
Constitutional Violations
- Illegal traffic stops without probable cause
- Excessive delay between arrest and testing
- Violation of the Fourth Amendment can invalidate evidence
Tips for Defending DUI Charges in Maryland
- Document Everything: Take detailed notes about the stop, testing procedures, and environmental conditions.
- Request Calibration and Maintenance Records: Ensures breathalyzer or other equipment met standards.
- Challenge Field Sobriety Test Validity: Medical conditions or improper administration can invalidate tests.
- Scrutinize Dash Cam Footage: Look for inconsistencies or errors in the officer’s account.
- Seek Expert Testimony: Professional witnesses can dispute scientific evidence or test methodology.
Common Misconceptions About DUI Evidence
- “Breath tests are infallible.” – Even small errors can drastically affect BAC readings.
- “Failing a field sobriety test means guilt.” – These tests are prone to false positives.
- “Dash cam footage always supports the officer.” – It can actually reveal procedural mistakes.
FAQs
Q1: Can I refuse a breathalyzer in Maryland?
A1: Yes, but refusal leads to administrative license suspension. An experienced DUI attorney can help navigate options.
Q2: How accurate are field sobriety tests?
A2: Accuracy varies; environmental factors, fatigue, and medical conditions can cause incorrect results.
Q3: Will dash cam footage always help my case?
A3: Not always, but it provides an independent record that can sometimes support defense arguments or expose procedural errors.
Call to Action
DUI evidence in Maryland is complex and often misinterpreted. At The Law Office of Hillel Traub, P.A., we specialize in analyzing DUI evidence, challenging flawed tests, and protecting our clients’ rights.
Call today for a free consultation to discuss your case and explore your defense options.
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