Idaho DUI Defenses | Field Sobriety Tests (FSTs)

Often, in order to determine if a driver is intoxicated, a police officer will have the driver perform a number of Field Sobriety Tests. These Field Sobriety Tests or "FSTs" are used by law enforcement to obtain probable cause thereby allowing them to initiate a breath or blood test.

Idaho DUI Lawyers | DUI Defense FSTs
Idaho DUI Defense | Boise DUI Lawyers | Idaho FSTs

Field Sobriety Test's (FSTs)

There are three Field Sobriety Test's (FST's) that officers commonly utilize during a DUI investigation:

  • The Horizontal Gaze Nystagmus (HGN)
  • The Walk-and-Turn (WAT)
  • The One-Leg Stand (OLS) 

These are the only three field sobriety tests endorsed by the National Highway Traffic and Safety Administrations (NHTSA), thus they are referred to as "Standardized" Field Sobriety Tests.

Although considered standardized, these tests have been widely criticized as designed to fail. There are many factors that can affect a driver's performance on the FST's:

  • Age
  • Injury
  • Disease
  • Uneven surface
  • Poor footwear
  • Eye conditions
  • Diseases that affects their ability to follow the object

And many others. Any of these factors could lead an officer to improperly conclude that you are impaired. Even under perfect conditions a sober driver would have difficulty passing these tests.

FST #1 - Horizontal Gaze Nystagmus

This is an involuntary jerking of the eye that occurs when the eyes move from side to side. The test requires the driver to look forward at a small object, usually the officer's finger, pen, or a small flashlight and follow the object with their eyes as he moves it side to side. The drivers head is to remain still during the test.

Officers look for three indicators of impairment when administering this test

  1. An inability to follow the moving object smoothly
  2. Distinct eye jerking when the eye is at maximum deviation (the point at which the eye has moved fully to one side)
  3. Whether the jerking of the eye is within 45 degrees of center  

FST #2 - Walk-and-Turn

This tests the driver's ability to complete tasks with divided attention. Law enforcement officers believe that the inability to perform a task that requires divided attention is a sign of intoxication.

During this test, the driver is instructed to walk, touching heel-to-toe on each step, along a straight line, turn, and walk the straight line back to the start.

The officer will look for several indicators of impairment

  1. If the driver cannot keep their balance
  2. Walking before the instructions are finished
  3. Stopping in the middle of the test
  4. Failure to touch heel-to-toe
  5. Steps off the line
  6. Takes the wrong number of steps
  7. Makes an improper turn.

FST #3 - One-Leg Stand

This is also a divided attention test.  The driver is instructed to stand with one leg in the air approximately six inches off the ground while counting to a certain number.

The officer looks for indicators of impairment, including:

  1. Swaying
  2. Difficulty counting
  3. Using their arms to keep balance
  4. Putting the foot down

Hire An Experienced DUI Attorney 

An experienced DUI attorney will be able to show how difficult these tests are to pass, even sober, and what factors the officer failed to take into account when administering the tests.

Free DUI Consultation

Idaho's Premier Criminal Defense and DUI Attorneys

We are committed to providing every client with the respect and compassion they deserve. We work one-on-one with our clients to provide them with the best possible defense. Let us help you. Boise DUI AttorneysBoise Criminal Defense

Free Consultations

Each case is unique. The strength and weakness of your case will depend on the particular facts of your case. Contact us to discuss your Criminal Defense or DUI case. We will explain the process and give you an honest assessment of the case.

Idaho Criminal Defense
Schofield and Young
Mon: 08:30am - 05:00pm
Tue: 08:30am - 05:00pm
Wed: 08:30am - 05:00pm
Thu: 08:30am - 05:00pm
Fri: 08:30am - 05:00pm