This is the first part of our new DUI Series which will outline each segment of a DUI stop and arrest from start to finish. This is to better educate the public regarding DUI and to become more knowledgeable about the process and legal rights involved.
A DUI case has three detection phases – (1) Vehicle in Motion; (2) Personal Contact; and (3) Pre-arrest Screening. Field sobriety tests are conducted in the pre-arrest screening.
During the first phase, law enforcement is taught to observe the vehicle and try to find any cues or clues that would indicate to the officer that there is a driving under the influence taking place. There are a whole host of cues (24) which are divided into four separate categories as defined by the NHTSA. I will not detail every single one but just gloss over the basics.
The first category includes problems maintaining proper lane position such as, straddling a lane line, wide turning radius, zigzagging and weaving across lane lines.
The second category includes issues with speeding and braking – accelerating and/or decele
rating rapidly, jerky stops, and driving slower than ten m.p.h. below the speed limit.
The third category includes vigilance problems – slowly responding to traffic signals, slow or failure to respond to officer’s lights, siren or hand signals, failure to signal or signaling inconsistent with driving actions, and so on.
The fourth category includes judgment problems – following too closely, unsafe lane changes, unusual behavior, turning abruptly or illegally, and appearing to be impaired.
After the officer has determined to stop the suspect, the officer then must observe how that suspect responds. This is determined by ten cues such as, difficulty with controls, exiting the vehicle, fumbling with license or registration, balance issues, leaning on objects, slurred speech, odor of alcoholic beverages from driver, and so forth.
The second phase now begins. This is the personal contact phase. At this point, the officer uses all of his senses and experience to find clues or cues of impairment: slurred speech, admission of drinking, alcohol containers, drugs, bloodshot eyes, etc. After this point, the officer then must decide whether to ask the driver of the vehicle to step outside of the car. Once the driver has stepped outside of the vehicle then the officer will conduct the third phase which is pre-arrest screening – the field sobriety tests. Field sobriety tests consist of three standardized tests: (1) Horizontal Gaze Nystagmus; (2) Walk and Turn; and (3) One Leg Stand.
Next up in our DUI Series – Field Sobriety Tests.