Alveolar Breath – Breath from the deepest part of the lung.

Blood Alcohol Concentration (BAC) – the percentage of alcohol in a person’s blood.

Breath Alcohol Concentration (BrAC) – The percentage of alcohol in a person’s breath, taken from deep in the lungs.

Clue – Something that leads to the solution of a problem.

Cue – A reminder or prompting as a signal to do something. A suggestion or hint.

Divided Attention Test – A test which requires the subject to concentrate on both mental and physical tasks at the same time.

DWI/DUI – The acronym “DWI” means driving while impaired and is synonymous with the acronym “DUI”, driving under the influence or other acronyms used to denote impaired driving. These terms refer to any and all offenses involving the operation of vehicles by persons under the influence of alcohol and/or other drugs.

DWI Detection Process – The entire process of identifying and gathering evidence to determine whether or not a suspect should be arrested for a DWI violation. The DWI detection process has three phases:

  • Phase One – Vehicle in Motion
  • Phase Two – Personal Contact
  • Phase Three – Pre-arrest Screening

Evidence – Any means by which some alleged fact that has been submitted to investigation may either be established or disproved. Evidence of a DWI violation may be of various types:

  • a.  Physical (or real) evidence: something tangible, visible, or audible.
  • b.  Well established facts (judicial notice).
  • c.  Demonstrative evidence: demonstrations performed in the courtroom.
  • d.  Written testimony or documentation.
  • e.  Testimony.

Field Sobriety Test – Any one of several roadside tests that can be used to determine whether a suspect is impaired.

Horizontal Gaze Nystagmus (HGN) – An involuntary jerking of the eyes as they gaze toward the side.

Illegal Per Se – Unlawful in and of itself. Used to describe a law which makes it illegal to drive while having a statutorily prohibited Blood Alcohol Concentration.

Nystagmus – An involuntary jerking of the eyes.

One Leg Stand (OLS) – A divided attention field sobriety test.

Personal Contact – The second phase in the DWI detection process. In this phase the officer observes and interviews the driver face to face; determines whether to ask the driver to step from the vehicle; and observes the driver’s exit and walk from the vehicle.

Pre-arrest Screening – The third phase in the DWI detection process. In this phase the officer administers field sobriety tests to determine whether there is probable cause to arrest the driver for DWI, and administers or arranges for a preliminary breath test.

Preliminary Breath Test (PBT) – A pre-arrest breath test administered during investigation of a possible DWI violator to obtain an indication of the person’s blood alcohol concentration.

Psychophysical – “Mind/Body”. Used to describe field sobriety tests that measure a person’s ability to perform both mental and physical tasks.

Standardized Field Sobriety Test Battery – A battery of tests, Horizontal Gaze Nystagmus, Walk and Turn, and One-Leg Stand, administered and evaluated in a standardized manner to obtain validated indicators of impairment on NHTSA research.

Tidal Breath – Breath from the upper part of the lungs and mouth.

Vehicle in Motion – The first phase in the DWI detection process. In this phase the officer observes the vehicle in operation, determines whether to stop the vehicle, and observes the stopping sequence.

Vertical Gaze Nystagmus – An involuntary jerking of the eyes (up and down) which occurs when the eyes gaze upward at maximum elevation.

Walk and Turn (WAT) – A divided attention field sobriety test.