|
|
FIELD SOBRIETY
TESTS |
|
|
Computing a BAC Estimate: How alcohol levels BAC are calculated |
Calculate your estimated BAC based
on what and how much you have had to drink.The results that are generated
are rough estimates of an average healthy person's BAC assuming typical
beverage sizes, recipes and alcohol content. The
Drink Wheel On-Line BrAC Calculator
A person's actual BAC is dependent on many complex factors,
including their physical condition (body composition, health etc...) and
what they have recently ingested (including food, water, medications and
other drugs). This site includes a more detailed discussion of the .
Field Validation of Standardized Field Sobriety
Tests (SFSTs) at Lower BAC Limits. Standardized
Field Sobriety Tests (SFSTs), used routinely by law enforcement since the
mid-1980s, were originally validated at the .10 BAC level. Now that many
states have lowered their BAC limit to .08 BAC, there was a need
to determine whether these standardized tests are also appropriate for use
at the new, lower BAC limit. This report summarizes field findings. SFST
materials are only available to law enforcement.
DOT HS 808 839 (Order # 7P0110)
Standardized Field Sobriety Testing (SFST) and Drug Recognition Expert (DRE) Training Programs. These training programs are provided to states and communities for law enforcement officers. A training curriculum is available for each program to train instructors. NHTSA and IACP have developed standards for the DRE and SFST programs. Available through state highway safety offices or through NHTSA regional offices.
Standardized Field Sobriety Testing
The Standardized Field Sobriety Test (SFST) is a battery of three tests administered and evaluated in a standardized manner to obtain validated indicators of impairment and establish probable cause for arrest. These tests were developed as a result of research sponsored by the National Highway Traffic Safety Administration (NHTSA) and conducted by the Southern California Research Institute. A formal program of training was developed and is available through NHTSA to help police officers become more skillful at detecting DWI suspects, describing the behavior of these suspects, and presenting effective testimony in court. Formal administration and accreditation of the program is provided through IACP. The three tests of the SFST are:
-
- the horizontal gaze nystagmus (HGN)
- the walk-and-turn
- the one-leg stand.
These tests are administered systematically and are evaluated according to measured responses of the suspect.
HGN Testing
Horizontal gaze nystagmus is an involuntary jerking of the eyeball which
occurs naturally as the eyes gaze to the side. Under normal circumstances,
nystagmus occurs when the eyes are rotated at high peripheral angles.
However, when a person is impaired by alcohol, nystagmus is exaggerated
and may occur at lesser angles. An alcohol-impaired person will also often
have difficulty smoothly tracking a moving object. In the HGN test, the
officer observes the eyes of a suspect as the suspect follows a slowly
moving object such as a pen or small flashlight, horizontally with his
eyes. The examiner looks for three indicators of impairment in each eye:
if the eye cannot follow a moving object smoothly, if jerking is distinct
when the eye is at maximum deviation, and if the angle of onset of jerking
is within 45 degrees of center. If, between the two eyes, four or more
clues appear, the suspect likely has a BAC of 0.10 or greater. NHTSA
research indicates that this test allows proper classification of
approximately 77 percent of suspects. HGN may also indicate consumption of
seizure medications, phencyclidine, a variety of inhalants, barbiturates,
and other depressants.
Divided Attention Testing
The walk-and-turn test and one-leg stand test are “divided
attention” tests that are easily performed by most sober people.
They require a suspect to listen to and follow instructions while
performing simple physical movements. Impaired persons have difficulty
with tasks requiring their attention to be divided between simple mental
and physical exercises.
In the walk-and-turn test, the subject is directed to take nine steps, heel-to-toe, along a straight line. After taking the steps, the suspect must turn on one foot and return in the same manner in the opposite direction. The examiner looks for seven indicators of impairment: if the suspect cannot keep balance while listening to the instructions, begins before the instructions are finished, stops while walking to regain balance, does not touch heel-to-toe, uses arms to balance, loses balance while turning, or takes an incorrect number of steps. NHTSA research indicates that 68 percent of individuals who exhibit two or more indicators in the performance of the test will have a BAC of 0.10 or greater. In the one-leg stand test, the suspect is instructed to stand with one foot approximately six inches off the ground and count aloud by thousands (One thousand-one, one thousand-two, etc.) until told to put the foot down. The officer times the subject for a 30 seconds. The officer looks for four indicators of impairment, including swaying while balancing, using arms to balance, hopping to maintain balance, and putting the foot down. NHTSA research indicates that 65 percent of individuals who exhibit two or more such indicators in the performance of the test will have a BAC of 0.10 of greater.
The effectiveness of SFST in court testimony and evidence depends upon the cumulative total of impairment indicators provided by the three-test battery. The greater the number of indicators, the more convincing the testimony. Because SFST is administered according to national standards and is supported by significant research, it has greater credibility than mere subjective testimony.Alternative Testing Methods
Sometimes, an officer will encounter a disabled driver who cannot perform the SFST. In such cases, some other battery of tests such as counting aloud, reciting the alphabet, or finger dexterity tests may be administered. Several appellate court decisions have indicated that, if you administer a test that requires the subject to respond orally in other than a routine information-giving fashion, such as requiring them to indicate the date of their sixth birthday, and if they are in custody at the time, you should administer the Miranda warning first, because you are seeking information from them that is testimonial or communicative in nature.
Field Validation of Standardized Field Sobriety Tests (SFSTs) at Lower BAC Limits
Standardized Field Sobriety Tests (SFSTs), used routinely by law
enforcement since the mid-1980s, were originally validated at the .10 BAC
level. Now that many states have lowered their BAC limit to .08 BAC, there
was a need to determine whether these standardized tests are also
appropriate for use at the new, lower BAC limit. This report summarizes
field findings. SFST materials are only available to law enforcement.
Refusal to submit to a breath or blood test
Look here in the future for information about
refusals. Our apologies for the delay. You may call Mr. Moore's
office to schedule an interview and discuss this issue.
PAS roadside breath test (preliminary alcohol screen test)
Preliminary Breath Testing Instruments ( PAS : Preliminary Alcohol Screening device )
PBT instruments are portable instruments for the purpose of BAC screening as part of the pre-arrest field testing. The suspect driver blows for several seconds through a plastic or glass tube, and the PBT provides an instantaneous determination of blood alcohol content.
In most jurisdictions, the legal basis for the use of these instruments is contained in the implied consent laws. While results of a PBT generally are not admissible as evidence of DWI, they do provide officers with additional objective information to establish probable cause for arrest and further chemical testing. They also help to detect persons who may be suffering from an illness or injury such as diabetes or head injury and are in need of chemical treatment, but would otherwise be mistaken for an intoxicated person. There are essentially three types of PBTs: electro-chemical, semi-conductor, and disposable chemical.
In electro-chemical PBTs, alcohol in the breath is absorbed into a fuel cell where it is oxidized, producing electrical current. The higher the alcohol content of the breath, the greater the current output of the fuel cell. By measuring the current produced, the instrument determines the breath alcohol content, and the BAC conversion is displayed with the aid of a computer chip. In semi-conductor PBTs, alcohol increases the electrical output of the semi-conductor. By measuring the voltage output, the breath alcohol content can be determined and the BAC conversion is displayed.
Disposable chemical PBTs are glass or plastic tubes containing a measured amount of the chemical, which is reactive with alcohol. As the suspect exhales through the tube, alcohol contained in the breath reacts with the chemical contained within. The greater the breath alcohol content, the greater the chemical reaction observed.
Look here in the future for information about PAS. You may call Mr. Moore's office to schedule an interview and discuss this issue.
|
Phone:
(800) 609-1060 |
||||||||||