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Police Evidence

Driving Under the Influence (DUI), or Driving While Intoxicated (DWI) evidence is collected in DUI cases from the time California Highway Patrol (CHP) officers, federal or local police officers, or sheriff's deputies see a motorist driving, contact a motorist at the scene of an accident, or find a person sleeping in a car. Once personal contact with a suspected driver is made, law enforcement officers continue to collect evidence to be used in a California criminal DUI prosecution.

The first type of DUI evidence collected in a DUI case are the observations of the California Highway Patrol officer, federal or local police officer or sheriff’s deputy. This evidence typically includes what the officer says he or she saw once they made personal contact with the driver at the window of the car. Personal contact consists of the initial contact with the driver until the subject is booked for driving under the influence.

The observations which are typically reported following a police officer’s personal contact include difficulty with the vehicle’s controls, bloodshot and watery eyes, odor of an alcoholic beverage emanating from the interior of the car, fumbling with license and registration documents, and slurred speech.

Upon making these observations, the police officer will usually order the driver suspected of driving under the influence out of the car. The officer will then continue to gather evidence and report whether the driver had difficulty getting out of the car, balance problems once getting out of the car, use of the car for balance, swaying, staggering or an unsteady gait. Next the officer will report whether the person had an odor of an alcoholic beverage emanating from their breath or person. Oftentimes, the driver may admit to having consumed an alcoholic beverage. Upon making the initial observations, the officer will move to the next phase of collecting evidence which includes asking the driver to perform so-called field sobriety tests (FST’s). Notably, California DUI officers are trained not tell the motorist that they are not required to perform Field Sobriety Tests.

DUI field sobriety tests (FST’s) may consist of several types of exercises. Three Field Sobriety Tests have been validated by the United States Department of Transportation’s National Highway and Traffic Administration (NHTSA) as Standardized Field Sobriety Tests (SFST’s), while the others are not standardized and may have actually been rejected by the National Highway and Traffic Administration (NHTSA) as Standardized Field Sobriety Tests (SFST’s). Nonetheless, these non-standardized Field Sobriety Tests are often used by California Highway Patrol officers, federal and local police officers or sheriff’s deputies.

Standardized Field Sobriety Tests (SFST’s) consist of three exercises and the California Highway Patrol DUI enforcement manual recommends officers perform the Standardized Field Sobriety Tests before administering any other type of Field Sobriety Test. The three Standardized Field Sobriety Test exercises are Horizontal Gaze Nystagmus (HGN), One Leg Stand, and Walk and Turn.

Horizontal Gaze Nystagmus (HGN) is more of an eye examination rather than a test. Because of its unique nature, the California Highway Patrol DUI Enforcement Manual recommends that it should only be used and relied upon by officers who have received formal training in its administration. In an HGN examination, the officer prepares by determining whether the driver is wearing eyeglasses or contact lenses, positions the driver to stand with his or her feet together and hands at their sides, while keeping their head still. Once this is accomplished, the officer is supposed to hold a stimulus (finger, pen, or penlight) approximately twelve (12) to fifteen (15) inches in front of the nose of the subject and slightly above eye level.

The actual Horizontal Gaze Nystagmus examination consists of the officer moving the stimulus in front of the eyes of the driver to determine whether the eyes smoothly pursue the stimulus, nystagmus at the right and left extremes, and whether there is an onset of nystagmus prior to forty-five (45) degrees. Nystagmus is the involuntary jerking of the eyes, while Horizontal Gaze Nystagmus is the involuntary jerking of the eyes as they move along the horizontal plane.

The One Leg Stand is a Standardized Field Test (SFST) which requires the subject to stand on one leg while the other leg is extended in front with the foot held approximately six (6) inches above the ground. The subject is to stare at the elevated foot and count out loud in a designated fashion for thirty (30) seconds.

Walk and Turn test requires the driver to stand in a heel to toe fashion with the arms at the sides. The driver is then instructed to take nine (9) heel to toe steps along a straight line, turn 180 degrees and take another nine (9) heel to toe step along a line. (The line is either real or imaginary.) All of this must be done while counting the steps audibly, keeping the arms at one’s side and looking at the feet. Many officers do not administer this Field Sobriety Test, citing officer safety concerns.

Accordingly to the CHP DUI Enforcement Manual, non-standardized Field Sobriety Tests should be used if the Standardized Field Sobriety Tests cannot be given. They consist of the Romberg balance test, finger to nose test, hand pat test, finger count test, and verbal and written alphabet test. Additional so-called Field Sobriety Tests have been developed by unknown California Highway Patrol officers, local police officers or sheriff’s deputies. They are limited only by the imagination of the officer and include counting backwards from designated numbers.

Preliminary Alcohol Screening (PAS) devices are used to obtain an approximate blood alcohol concentration (BAC) from the person suspected of driving under the influence. Usually administered after all other Field Sobriety Tests have been administered, the most common PAS device used in California is the Alcosensor IV, manufactured by Intoximeters. If the PAS device indicates a blood alcohol level of 0.08 percent or higher through use of an electro-chemical sensor, a driver is almost always arrested. In fact, a driver can be arrested for DUI even if the PAS device shows a blood alcohol level of less than 0.08 percent.

The driving observations, observations of the driver after contact, performance on the so-called Field Sobriety Tests, and results from the Preliminary Alcohol Screening (PAS) device are calculated to precede the administration of a chemical test. The three types of chemical tests are breath alcohol test, blood test, or urine test. Presently, urine tests are seldom administered in California unless the driver is suspected of being under the influence of medication or drugs or if the two other tests are not available.

Breath alcohol testing is the most common chemical test administered. There are several devices used to collect this evidence. The Intoxilyzer 5000 is a desktop machine utilizing infrared spectroscopy and manufactured by CMI. There are several versions of this device and it is no longer manufactured. Many of these machines have been in service for over twenty (20) years and require continual maintenance.

Drager manufactures two breath test machines which are used by California law enforcement agencies. The most common Drager device is the Alcotest 7110. This evidential breath test machine utilizes infrared spectroscopy and electrochemical fuel cell technology. The manufacturer contends two different and independent measuring systems provide the highest level of forensic and legal integrity available.

The second Drager breath test machine in service in California is the 7410. Like the Alcosensor Preliminary Alcohol Screening device, the 7410 utilizes electrochemical fuel cell technology. The Drager 7410 is portable and is also called the EPAS (Evidential Preliminary Alcohol Screening device) as it can serve as both the Preliminary Alcohol Screening device, as well as the evidential chemical test.

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