Are field sobriety tests reliable?

When a police officer suspects someone of driving under the influence there is a process he or she must follow. In order to make an arrest, the officer must first find probable cause to take action.

One of the most common ways of doing so is by requesting the driver to submit to a field sobriety test. There are a variety of tests that an officer may ask the driver to perform, each of which have the potential to provide the police with probable cause to make an arrest.

But what happens if the test gives an inaccurate result? Can you trust a field sobriety test to provide reliable evidence? These are important questions given the harsh penalties associated with a DUI arrest.

An imperfect practice

Field sobriety tests can be very helpful. They often provide visual evidence of a driver’s decision to drink and drive, effectively removing a dangerous driver from the road. The problem is that field sobriety tests are not 100% accurate. In fact, the figure is actually significantly less than perfect.

The three most common field sobriety tests are the one-leg stand, walk-and-turn and horizontal gaze nystagmus, which refers to the officer checking the driver’s eyes for exaggerated eye jerks. A study performed by the National Highway Traffic Safety Administration and Southern California Research Institute resolved that all three tests are imperfect.

The one-leg stand had the lowest accuracy rate at 65%, followed by the walk-and-turn at 68% and horizontal gaze nystagmus at 77%. Administering all three tests in conjunction bumps the figure up to 82%. Point being, field sobriety tests are a helpful but imperfect tool and therefore arguable in a court of law.

Reasons for inaccuracy

There are a number of different reasons that field sobriety tests can be unreliable. In fact, it is entirely possible that a person who has not had a sip of alcohol could fail. People with mental or physical impairments in particular are susceptible to failed tests.

Anxiety or general nervousness, for example, may mimic signs of alcohol use in the context of a field sobriety test. Officers do not have a frame of reference to judge your speaking and movements from, which also increases the likelihood of error.

Other common reasons for inaccuracy include:

  • Physical handicap or injury
  • Lack of coordination
  • Poor balance
  • Obesity
  • Advanced age

If you suspect that an inaccurate field sobriety test contributed to your DUI arrest, make sure to contact an experienced professional to help you navigate your case.

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