September 22, 2026

DUI Field Sobriety Guide for Maryland Drivers

A flashing patrol light in the rearview mirror can make even a routine drive feel overwhelming. If an officer asks you to step out of the car and perform roadside exercises, this DUI field sobriety guide can help you understand what is happening, what these tests are designed to show, and why the details of a traffic stop matter in a Maryland DUI or DWI case.

Field sobriety testing is not a medical examination, and it does not produce a simple pass or fail result. It is an officer’s roadside assessment, often made under stressful conditions and later used as part of the evidence in court. Knowing the process will not make the situation easy, but it can help you respond calmly and recognize when you need legal advice.

What Field Sobriety Tests Are Meant to Measure

Police officers use field sobriety tests to look for signs they associate with impairment. The most commonly used standardized tests were developed to assess balance, coordination, attention, and certain eye movements. Officers also rely on their observations before and during the exercises, including the way a driver speaks, follows instructions, exits a vehicle, or maintains balance.

The key word is observations. These tests are subjective to a degree. An officer must interpret what they see, and factors unrelated to alcohol or drugs can affect performance. Uneven pavement, poor lighting, rain, heavy traffic, cold weather, fatigue, injuries, anxiety, footwear, age, and medical conditions may all matter.

That does not mean a test result automatically disappears from a case. It does mean the circumstances should be examined carefully. A DUI defense attorney may review whether the officer selected an appropriate location, gave standardized instructions, documented the stop accurately, and considered explanations for apparent clues of impairment.

The Three Standard Tests in a DUI Field Sobriety Guide

Many Maryland roadside investigations include one or more of three commonly recognized standardized field sobriety tests. Not every stop follows the same pattern, and an officer may use additional observations or nonstandard exercises. Still, these are the tests drivers are most likely to encounter.

Horizontal Gaze Nystagmus

For the horizontal gaze nystagmus test, an officer asks a driver to follow a stimulus, such as a pen or fingertip, with their eyes. The officer looks for involuntary eye movements they may associate with alcohol impairment.

This test can sound straightforward, but proper administration matters. The officer must position the stimulus correctly, check each eye, move it at the appropriate speed, and account for certain medical or environmental factors. Flashing emergency lights, passing headlights, vision issues, and head injuries can complicate the observation. The test also requires training and careful explanation if it is later presented in court.

Walk-and-Turn

The walk-and-turn exercise asks a driver to take heel-to-toe steps along a real or imaginary line, turn in a specific way, and return using the same steps. The officer watches for things such as starting too soon, missing heel-to-toe contact, stepping off the line, using arms for balance, making an improper turn, or taking the wrong number of steps.

The exercise divides attention between listening, remembering, balancing, and moving precisely. That is the point, but it also explains why a sober person may struggle. Someone with a knee, back, ankle, or inner-ear condition may have legitimate difficulty. So may a driver wearing work boots, heels, sandals, or shoes with poor traction on a sloped shoulder.

One-Leg Stand

In the one-leg stand, the driver is asked to raise one foot and hold it off the ground while counting as instructed. Officers may look for swaying, hopping, putting the foot down, or using arms to maintain balance.

Like the walk-and-turn, this exercise is sensitive to the setting. A person can have trouble standing on one leg for reasons that have nothing to do with alcohol or drug impairment. The surface, weather, footwear, body type, injury history, and the officer’s instructions can all affect the result.

What to Do During a Maryland DUI Stop

The most helpful approach is calm, respectful, and careful. Pull over safely, keep your hands visible, provide the documents the officer lawfully requests, and avoid sudden movements. You do not need to argue your case on the roadside, and volunteering extra information rarely improves the situation.

You can ask whether you are free to leave. If you are not, keep your answers brief and polite. Do not lie, physically resist, or interfere with the officer. Those choices can create additional problems separate from the original traffic stop.

It is also reasonable to communicate relevant physical limitations. If you have an injury, a neurological condition, balance problems, or another issue that could affect an exercise, state that clearly and respectfully. Do not assume the officer will notice it. If possible, remember the details later: the road conditions, lighting, weather, footwear, what the officer said, and whether you told the officer about a medical concern.

Field Sobriety Tests Are Different From Chemical Testing

One of the most confusing parts of a DUI investigation is that roadside exercises and chemical tests are not the same thing. Field sobriety tests involve an officer’s observations. A preliminary breath test at the roadside may also be requested, while an evidentiary breath or blood test may come later, usually after an arrest.

Maryland’s implied-consent rules can carry serious consequences for a driver who refuses a post-arrest chemical test or has a high test result. Those consequences can include Motor Vehicle Administration penalties and may affect driving privileges. The exact options and deadlines depend on the facts of the stop, the test requested, your prior record, and the paperwork you receive.

Because these issues are time-sensitive, do not treat a DUI arrest as something to address after the court date arrives in the mail. Preserve every document, including citations, charging papers, any advice-of-rights form, and MVA notices. A lawyer can explain the criminal case and the separate administrative process, which often move on different timelines.

How Field Sobriety Evidence Can Be Challenged

A DUI charge is serious, but an arrest is not a conviction. The prosecution still has the burden to prove its case, and roadside testing is only one part of the evidence. A careful review may raise questions about why the stop occurred, whether the officer had a valid basis to extend the encounter, and how the tests were performed.

The video evidence can be especially significant. Body-camera footage, dash-camera footage, and dispatch records may show details that do not appear in a police report. For example, a report may say a driver was unsteady, while video may reveal an uneven shoulder, confusing instructions, or a driver who was cooperative and steady in other moments.

The facts can cut both ways. Some cases involve clear driving behavior, strong observations, or a reliable chemical test. Others involve weak testing conditions, medical explanations, or problems with the stop itself. Practical legal advice starts with an honest review of the evidence, not a one-size-fits-all promise.

Steps to Take After a DUI or DWI Arrest

After release, write down everything you remember while it is fresh. Include where you were stopped, what you had to eat or drink, any medications you take, the timeline of the evening, and the officer’s instructions. Save receipts, rideshare records, text messages, and names of people who saw you before driving when they may help establish the timeline.

Avoid discussing the incident on social media or trying to contact witnesses to coordinate stories. Do not ignore court notices, MVA paperwork, or conditions of release. If your license was taken or you were given a temporary license, the deadline to protect your driving privileges may be short.

A conversation with an experienced Maryland DUI attorney can bring order to a confusing situation. Montero Law Group helps clients understand the allegations, deadlines, possible license consequences, and realistic defense options without adding unnecessary pressure to an already stressful moment.

A roadside test may feel like the entire case is decided on the shoulder of the road. It is not. The details, the procedures, and the next steps all deserve careful attention, especially when your license, work, and peace of mind are on the line.