Written by attorney Leonard D. Harden

Field Sobriety Tests, What do they mean?

Roadside Tests, What do they Mean?

The police are trained to perform roadside tests to determine if a person should be arrested. These roadside tests are called the standardized field sobriety tests. The reality of the roadside field sobriety tests is that they are conducted by the officer in an attempt to gather information to support an arrest.

There are three phases an officer is trained to detect a DWI: (1) Vehicle in motion, (2) Personal contact, and (3) Pre-arrest screening. The roadside tests are the final part of an officers training to detect DWI. At the conclusion of this phase the officer must decide whether to arrest or let a person go. The purpose of these tests is to get information to determine if there is probable cause to believe that a person is impaired and whether to arrest that person.

Probable cause to arrest is a very low standard. It is defined in NH as where the facts and circumstances within the officer’s knowledge and of which he has reasonably trustworthy information are sufficient in themselves to warrant a man of reasonable caution in the belief that the person to be arrested has committed an offense. State v. Schofield, 114 NH 454 (1974). In short, an officer may arrest if a reasonable person would believe that a crime occurred and the person to be arrested committed the crime. This very subjective decision is left to each officer.

The field sobriety tests are based on a series of studies done in the mid 1970’s to try to determine the most effective tests to help officers make correct arrest decisions. The goal of these studies was to give the police some objective criteria to enable officers to support arrest decisions.

The conclusion of those studies resulted in a battery of standardized field sobriety tests called: Horizontal Gaze Nystagmus (pen test); Walk and Turn Test (walk the line); and One Leg Stand (counting on a leg). These three physical tests are required to be performed in a standardized and prescribed manner or they will lose there validity.

These tests even if done perfectly still have a significant error rate. The pen test is purported to be 77% accurate, the walk the line test is 67% accurate and the counting on a leg is 65% accurate. This means that approximately 1 in 4 people will fail the pen test, and 1 in 3 people will fail the balance tests even when absolutely sober.

These roadside tests are also dependent on the average healthy person. If you take medications, have head injuries, have lower back, knee, hip, ankle issues these tests can be affected. It is important that if you are taking these tests that you honestly relay any medical issues you suffer to the officer. If you were not asked about your medical situation out on the road, be sure to relay that to the DWI attorney. It is vital that a DWI attorney learn about any existing medical conditions or medications. A person’s medical conditions may significantly alter how they perform the roadside tests.

The field sobriety tests do not possess the scientific reliability of a chemical test but are admissible in Court. There is good NH law that indicates poor performance on the physical field sobriety tests is insufficient to prove a person guilty of DWI without any “significant corroboratory evidence."State v. Lorton, 149 NH 732 (2003) A skilled DWI attorney should be certified to perform these tests and have the same manuals that the police academy uses to train officers. The authors of this book have both undergone the same training as the police and possess the skills to properly administer these roadside tests. It is essential that a DWI attorney be an expert at the field sobriety tests. There are common errors that officers routinely make in giving these tests which can be used to keep out the tests and/ or show there unreliable nature.

The errors in administering or performing the field sobriety tests are a great opportunity for a skill DWI attorney to illustrate how well their clients performed. The tests themselves are scored very differently than any test given in a school. The tests are designed to fail not to produce passing results. These tests will be covered in greater detail in later chapters.

A skilled DWI attorney can turn the roadside field tests into an example of good performance and sobriety. A skilled DWI attorney knows when and how to attack a test to provide the maximum benefit for a client. It is important to hire a qualified, skilled DWI attorney who knows how to try a case to a judge and jury effectively.

The police may also use other roadside tests that have not been validated: Counting backwards; Modified Rhomberg Balance; Coin Pickup; Finger Dexterity; and Finger to Nose. These non-validated tests are often used when a person has expressed that they have a physical disability that would hinder their performance on a balance test. Additionally, some officers give these non standard tests in an effort to collect more evidence to use to prove impairment.

These non standard tests provide an even greater opportunity for a skilled DWI attorney to illustrate how their client was not given a fair test, or that the test has no validity to show impairment is more likely or less likely. If a person performs well on the non standard tests they may also be used to show sobriety.

The studies from the 1970’s determined that none of the non-validated tests could provide more than a 50% chance of determining whether a person was impaired. In other words these tests were equal to or less accurate than a coin flip. These non standard tests are also administered without any consistency. It is not uncommon for an officer to claim to have given the counting test, rhomberg, and finger to nose test according to the manual. However, when required to produce the standards for these tests none exists. Nonetheless it is interesting to the authors that these non standard tests persist given there lack of validity.

As stated previously, it is always vital to be polite and courteous to an officer who has made a stop. However, it is equally important to know your rights. There is no requirement to perform any roadside tests. These tests are voluntary, if an officer orders you out of your car you should comply, but if you are asked if you would agree to take some roadside tests, you should decline. A savvy driver should politely decline to perform any roadside tests. In fact a driver should not even exit their vehicle unless ordered to by the officer. The authors of this book have won cases as a result of the officers ordering people to take the roadside tests, rather than obtaining consent.


* Politely decline to give evidence to the police.

* Politely decline exiting your vehicle or performing any roadside tests.

* If ordered comply with an officer command.

* Provide accurate information regarding physical and medical issues.

* Contact the best qualified, most experienced and best DWI attorney.

Additional resources provided by the author

2006 NHTSA Student Manual, Detection and Standardized Field Sobriety Testing:

Free Q&A with lawyers in your area

Can’t find what you’re looking for?

Post a free question on our public forum.

Ask a Question

- or -

Search for lawyers by reviews and ratings.

Find a Lawyer