Field Sobriety Test Defense in Massachusetts

Massachusetts police use roadside field sobriety exercises to decide whether to make an OUI arrest. At trial, the Commonwealth may rely on the officer’s observations as evidence of balance, coordination, and the ability to follow instructions. The exercises are not chemical measurements, and their value depends on the legal basis for requesting them, the instructions, the surface, the conditions, the scoring, and the driver’s physical circumstances. The separate breathalyzer-defense page addresses the regulated police-station breath test.

When Police May Direct Field Sobriety Exercises

An officer may direct a driver to perform roadside field sobriety exercises when specific and articulable facts create reasonable suspicion of operating under the influence. In Commonwealth v. Blais, 428 Mass. 294, 297-302 & n.3 (1998), the Supreme Judicial Court held that the exercises are a reasonable part of a lawful investigative detention. The officer does not need the driver’s consent and does not need to advise the driver of a right to refuse.

That authority has limits. Police may not use physical force to make a driver perform the exercises. The officer must also have reasonable suspicion before extending the encounter for roadside testing. If that legal basis was absent, the defense may seek suppression of the observations as the product of an unlawful detention.

An officer’s statement that the exercises are mandatory does not automatically require exclusion when reasonable suspicion already supports a lawful direction. The statement becomes important when the Commonwealth must rely on voluntary consent, or when threats, force, or the surrounding circumstances exceeded the scope of a lawful investigative direction. In those settings, a misleading claim that compliance was mandatory may support a motion to suppress, but the result depends on the complete facts.

What Happens if a Driver Refuses

Declining roadside field sobriety exercises does not cause the automatic Registry suspension that follows refusal of the regulated police-station chemical test. The refusal itself is generally inadmissible as evidence of guilt under article 12 of the Massachusetts Declaration of Rights. In Commonwealth v. McGrail, 419 Mass. 774, 779-780 (1995), the Supreme Judicial Court treated the refusal as protected testimonial evidence.

The protection is not absolute after the defense opens the door. If the defense creates a misleading impression that the driver cooperated fully or that police never offered the exercises, the judge may permit limited refusal evidence to correct that impression. Commonwealth v. Beaulieu, 79 Mass. App. Ct. 100, 104 (2011). Statements and conduct while a person is attempting an exercise are different. A statement such as an inability to continue may be admissible even though a later actual refusal is not.

The Three Standardized Field Sobriety Tests

The National Highway Traffic Safety Administration recognizes a three-exercise standardized field sobriety test battery: horizontal gaze nystagmus, the walk and turn, and the one leg stand. NHTSA developed the battery to help officers estimate whether a person’s alcohol concentration was at or above a specified level. The research did not measure whether a particular person’s ability to drive was impaired.

NHTSA prescribes instructions, demonstrations, test conditions, and clue definitions. The current manual cautions that changing standardized elements may compromise validity. A departure does not produce automatic exclusion in every case, but it can disconnect the officer’s conclusion from the research used to support the battery. Video, the police report, and the officer’s testimony should be compared with the actual NHTSA procedure.

The Walk-and-Turn Exercise

The walk and turn asks the driver to stand heel to toe while listening, take nine heel-to-toe steps, complete a prescribed turn, take nine steps back, keep the arms down, watch the feet, and count aloud. The officer scores eight clues, including beginning too soon, stepping off the line, using the arms for balance, an improper turn, and taking the wrong number of steps.

The details matter. The officer often estimates a half-inch heel-to-toe gap and six inches of arm movement by sight. The line may be imaginary. The turn contains several separate instructions delivered once. A report may record two scored events without recording the correct steps, correct count, or successful completion. The defense compares each claimed clue with the video and the manual rather than accepting a summary that the driver passed or failed.

The One-Leg-Stand Exercise

The one leg stand asks the driver to raise one foot approximately six inches, keep both legs straight, point the raised foot forward, watch it, and count aloud for about 30 seconds. The officer scores swaying, using the arms for balance, hopping, and putting the foot down.

NHTSA does not quantify how much sway counts. The officer estimates the arm movement and decides whether an adjustment is a hop. Age, weight, back or leg conditions, inner-ear conditions, footwear, wind, temperature, lighting, and the surface can affect performance. The officer ordinarily has no sober baseline showing how that driver performs the exercise under comparable conditions.

Horizontal Gaze Nystagmus

Horizontal gaze nystagmus is an involuntary jerking of the eyes. The officer moves a stimulus while looking for lack of smooth pursuit, distinct and sustained nystagmus at maximum deviation, and onset before 45 degrees. The procedure specifies the stimulus distance, position, speed, order, and hold time. Video may show rushed passes, inconsistent positioning, or an abbreviated medical screen.

Massachusetts treats horizontal gaze nystagmus as scientific evidence. Under Commonwealth v. Sands, 424 Mass. 184 (1997), the Commonwealth must provide an adequate expert foundation before a jury may hear the result. A reference to HGN in a police report does not by itself establish admissibility.

Alphabet, Counting, Modified Romberg, and Finger-to-Nose Exercises

Police may also use an alphabet exercise, backward counting, a finger count, Modified Romberg, or finger to nose. These exercises are not part of the validated three-test standardized field sobriety battery. The NHTSA drug-recognition curriculum does prescribe administration procedures for Modified Romberg and finger to nose, but it also recognizes that those exercises have not undergone the same controlled validation as the three-test alcohol battery.

The distinction should be stated accurately. The exercises are not all instructionless, but they do not carry the validation claims assigned to the standardized battery. The defense examines the actual instructions, what the officer considered significant, whether the officer followed the applicable training, and whether the officer converted an observation into an unsupported scientific conclusion.

What the Jury May Hear

In an alcohol OUI case, an officer may ordinarily describe observed balance, coordination, and ability to follow instructions. The officer may also give a lay opinion about sobriety or intoxication. Under Commonwealth v. Canty, 466 Mass. 535 (2013), the witness may not answer the ultimate legal question whether the defendant operated under the influence or whether alcohol diminished the ability to operate safely.

For marijuana OUI allegations, the rules are narrower. In Commonwealth v. Gerhardt, 477 Mass. 775 (2017), the Supreme Judicial Court called them roadside assessments and prohibited testimony that a person passed or failed or that the performance established marijuana impairment. The witness may describe relevant observations, subject to the ordinary limits on lay opinion.

Conditions, Instructions, and Alternative Explanations

The walking exercises call for a reasonably dry, hard, level, and nonslippery surface. Lighting, traffic, cruiser lights, weather, footwear, injuries, fatigue, age, weight, language, anxiety, and unfamiliarity can affect what the officer sees. These facts do not automatically exclude the evidence. They can affect whether the officer followed the training and how much weight the judge or jury should give the observations.

The instruction phase is part of the evidence. The officer should be able to identify which instructions were given, whether they were demonstrated, whether questions were answered, and when scoring began. Body-camera and cruiser video may show a different surface, pace, demonstration, or performance from the written report.

Reviewing and Challenging the Officer’s Opinion

A useful review begins with the stop and asks whether reasonable suspicion supported the request for field sobriety exercises. It then compares the video, report, testimony, and training materials exercise by exercise. The review should identify correct performance as well as claimed clues, the testing conditions, the driver’s physical circumstances, and any words or conduct that the Commonwealth may try to characterize as an attempted performance rather than a protected refusal.

Attorney Serpa addresses the trial method in the firm’s article on cross-examining the field sobriety opinion. Related questions appear in the field sobriety test FAQs. The broader criminal and license framework appears on the Massachusetts OUI defense page.

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