Field Sobriety Tests Explained

How It's Performed:

• Officer holds stimulus (pen, finger) 12-15 inches from eyes
• Moves stimulus horizontally left and right
• Observes involuntary eye movements (nystagmus)
• Checks both eyes separately
• Takes 88 seconds when performed correctly
• Three stages of testing per eye

What Officer Looks For:

• Lack of smooth pursuit: Eyes don't track smoothly
• Distinct nystagmus at maximum deviation: Jerking when eyes look far left/right
• Onset of nystagmus prior to 45 degrees: Jerking starts before 45-degree angle
• Maximum 6 clues total (3 per eye)
• 4 or more clues indicates impairment

Instructions Phase:

• Stand heel-to-toe on imaginary line
• Keep arms at sides during instructions
• Listen to all instructions before starting
• Must maintain position during instruction
• Officer demonstrates proper technique

Walking Phase:

• Take 9 heel-to-toe steps on line
• Turn around using small choppy steps
• Return 9 heel-to-toe steps
• Count steps out loud
• Watch feet while walking
• Keep arms at sides

8 Clues of Impairment:

1. Cannot keep balance during instructions
2. Starts before instructions finished
3. Stops while walking
4. Does not touch heel-to-toe
5. Steps off line
6. Uses arms for balance
7. Improper turn
8. Wrong number of steps

Result: 2 or more clues indicates impairment (68% accuracy)

How It's Performed:

• Stand with feet together, arms at sides
• Raise one foot approximately 6 inches off ground
• Keep raised foot parallel to ground
• Stare at raised foot
• Count out loud: "one thousand one, one thousand two..."
• Continue for 30 seconds

4 Clues of Impairment:

1. Sways while balancing
2. Uses arms for balance
3. Hopping to maintain balance
4. Puts foot down before 30 seconds

Result: 2 or more clues indicates impairment (65% accuracy)