DelSignore Law’s Top 15 Reasons Field Sobriety Tests Are Inaccurate and Do Not Necessarily Show Alcohol Impairment

Charged with OUI in Massachusetts after allegedly failing field sobriety tests? Your performance on these roadside exercises may not tell the whole story.

For over 20 years, Massachusetts OUI Defense Attorney Michael DelSignore has defended individuals accused of operating under the influence of alcohol. One of the most important parts of his defense strategy is challenging the reliability of field sobriety tests.

Police officers frequently describe these tests as evidence that someone was impaired by alcohol. However, there are many reasons a person who is not impaired may have difficulty performing them.

The central question is whether your performance actually demonstrates alcohol impairment or whether there is another reasonable explanation for what the officer observed.

Attorney DelSignore carefully examines how the tests were administered, the conditions under which they were performed, and whether the officer accurately interpreted your performance.

The tests do not directly measure the amount of alcohol in your system or determine whether your ability to drive was diminished. Officers observe your performance on unfamiliar physical exercises and look for specific mistakes. Someone may have difficulty balancing on one foot or walking heel-to-toe without being impaired by alcohol.

Attorney DelSignore’s approach: Challenge the assumption that difficulty performing a balancing exercise necessarily means someone was impaired while driving.

Being stopped late at night, with flashing cruiser lights behind you and the possibility of arrest, can make anyone nervous. Anxiety can affect concentration and the ability to follow instructions. Starting too early or losing concentration does not necessarily establish alcohol impairment.

Attorney DelSignore’s approach: Examine whether the officer considered the stress of the encounter before attributing mistakes to alcohol.

The walk-and-turn test requires a person to remember how to walk, count steps, turn, and return. If instructions are given too quickly, a person may misunderstand what is required.

Attorney DelSignore’s approach: Review police video to determine whether instructions were clear and sufficient time was allowed.

Standardized testing procedures include demonstrations. If the officer does not properly demonstrate an exercise, the person may not understand what to do.

Attorney DelSignore’s approach: Compare the demonstration and instructions with standardized testing procedures.

Sloped shoulders, uneven pavement, and loose gravel can make balancing difficult. Appropriate testing surfaces matter.

Attorney DelSignore’s approach: Examine the testing location and whether the surface contributed to the alleged mistakes.

Rain, snow, ice, wind, and freezing temperatures may interfere with concentration and balance during roadside exercises.

Attorney DelSignore’s approach: Review the weather and whether it offers an alternative explanation for the observations.

High heels, sandals, flip-flops, dress shoes, and some boots can make balance exercises more difficult. NHTSA procedures address footwear in specified circumstances.

Attorney DelSignore’s approach: Determine whether the officer considered footwear and offered appropriate accommodations.

Back, knee, or ankle injuries, neurological conditions, and inner-ear disorders may affect balance even when a person is sober.

Attorney DelSignore’s approach: Identify relevant medical conditions and whether supporting evidence explains the alleged difficulties.

Older individuals may have difficulty maintaining balance or performing unfamiliar movements. NHTSA materials identify people over 65 as potentially having difficulty on certain tests.

Attorney DelSignore’s approach: Consider whether age and physical limitations were properly taken into account.

Weight, physical condition, and natural balance differ among individuals. NHTSA materials recognize that substantially overweight people may have difficulty with certain tests.

Attorney DelSignore’s approach: Challenge conclusions that ignore individual physical abilities.

Standardized tests have defined scoring criteria. The walk-and-turn has eight standardized clues and the one-leg stand has four. Not every minor movement is a recognized clue.

Attorney DelSignore’s approach: Examine each alleged clue and determine whether it was properly identified and scored.

An officer may emphasize stepping off the line or using arms for balance while overlooking correctly followed instructions, accurate counting, or completing most of the test successfully.

Attorney DelSignore’s approach: Present the complete performance rather than isolated mistakes.

Passing vehicles, flashing lights, nearby officers, or interruptions during the exercises may affect concentration.

Attorney DelSignore’s approach: Review video for distractions or interruptions that may have affected performance.

The research supporting standardized field sobriety tests evaluates their relationship with blood alcohol concentration. Predictive value does not make the tests infallible, and predicting BAC is not the same as proving impaired driving beyond a reasonable doubt.

Attorney DelSignore’s approach: Explain the limitations of the research and challenge claims that the tests conclusively prove impairment.

Safe driving, clear speech, producing documents without difficulty, walking normally, and normal coordination during booking may be relevant when the roadside test performance is characterized as substantially impaired.

Attorney DelSignore’s approach: Compare observations across the encounter to determine whether the evidence consistently supports impairment.

Attorney DelSignore does not assume that an officer’s conclusion about field sobriety tests is correct. With more than 20 years of experience defending Massachusetts OUI cases, he examines the actual evidence rather than relying solely on the police report.

He examines whether the officer followed standardized procedures, provided appropriate instructions, and conducted the exercises under reasonable conditions.

The police report may describe several mistakes, but video evidence may tell a different story. Attorney DelSignore reviews what you actually did, including the portions you performed correctly.

He evaluates the tests alongside driving observations, the initial interaction, and the booking process to identify weaknesses and inconsistencies in the Commonwealth’s case.

Yes. An officer’s conclusion that you failed field sobriety tests does not automatically mean you will be convicted of OUI. In Massachusetts, the Commonwealth must prove every element of the offense beyond a reasonable doubt. Test performance may be considered alongside the other evidence. Attorney DelSignore has defended OUI cases by challenging police observations and demonstrating reasonable doubt. Every case depends on its particular facts.

If you were arrested for OUI in Massachusetts and believe you performed poorly on field sobriety tests, do not assume your case cannot be defended. There may be weaknesses in the officer’s observations that are not apparent from the police report.

Attorney Michael DelSignore has spent over 20 years defending individuals charged with OUI throughout Massachusetts. He personally examines the evidence and develops a defense strategy based on the specific facts of each case.

Call or text Attorney DelSignore at 781-686-5924 to discuss your Massachusetts OUI charge and learn how the field sobriety test evidence may be challenged.