Evidence of Impairment – CDAC Member Portal

To prove DUI or DWAI, you must offer the jury evidence that the defendant drove while impaired. Your evidence of impairment will differ at least somewhat from case to case, but evidence of impairment tends to be similar across cases. The list of evidence below is just some of the evidence you might see in your impaired driving cases—and evidence you should elicit from your witnesses for the jury’s consideration. Many of the clues on this list are from the NHTSA SFST Refresher Manual.

Initial Observations

Illegal, dangerous, or unusual driving

- - Weaving
  - Drifting
  - Straddling lane line
  - Swerving
  - Turning in a wide radius
  - Unnecessary acceleration or deceleration
  - Speeding, varying speed, or driving more than 10 MPH under the limit
  - Stopping too far from the curb or at an inappropriate angle
  - Stopping too short or beyond a line
  - Stopping in lane for no apparent reason
  - Jerky or abrupt stops
  - Running red lights or stop signs
  - Illegal U-turns
  - Driving at night without lights
  - Careless or reckless driving
  - Slow response to traffic signals
  - Driving in opposing lane or wrong way
  - Failure to signal or signaling inconsistent with actual actions
  - Following too closely
  - Unsafe lane changes
  - Driving somewhere other than designated roadway

Unusual behavior

- - Disorientation
  - Inappropriate laughing
  - Unexplained crying
  - Dazed
  - Hallucinations
  - Slow reactions

Clothing and Body

- - Soiled
  - Excessively messy
  - Missing clothing
  - Fumbling fingers
  - Bruises, bumps, scratches

Balance and Body Movements

- - Swaying
  - Staggering
  - Stumbling
  - Falling
  - Poor coordination
  - Fumbling with driver license or registration
  - Difficulty exiting vehicle
  - Leaning on the vehicle

Breath

- - Smells like alcoholic beverage (strong, moderate, slight)
  - Smells like marijuana
  - Cover-up odors
  - Other unusual odors

Cognition

- - Repeating questions or comments
  - Slow to respond to officer
  - Officer must repeat statements or questions
  - Provides incorrect information
  - Changes answers

Speech

- - Slurred
  - Stammering
  - Shouting
  - Thick-tongued
  - Stuttered

Eyes

- - Bloodshot
  - Watery
  - Dilated or constricted pupils
  - Obvious nystagmus

Attitude

- - Excited
  - Sarcastic
  - Antagonistic
  - Profane
  - Uncooperative

State of Vehicle

- - Crashed
  - Poor parking, such as parking askew or facing the incorrect direction
  - Alcohol, drugs, or paraphernalia present in vehicle
  - Vehicle smells like alcohol or marijuana

Further Investigation

- - Results of Standardized Field Sobriety Tests
  - Refusal to complete SFSTs
  - Results of a portable breath test (not admissible at trial)
  - Admission of drinking or using drugs
  - Results of chemical tests, like a blood test
  - Evaluation of a Drug Recognition Expert (DRE)
  - Evidence obtained from witness interviews
  - Surveillance video