Alcohol Concentration
Chemical Testing in Texas
Under Texas law an individual is legally intoxicated if his alcohol
concentration is .08 or greater. Alcohol concentration can be
determined by testing the blood, urine or breath. “Alcohol
concentration” means the number of grams of alcohol per: (1) 210 liters of breath; (b) 100
milliliters of blood; or (c) 67 milliliters of
urine.
Blood testing is generally considered to be the most reliable and
accurate, while urine tests are regarded as the least precise. If you
are arrested for DWI in Texas you will most likely be asked to give a
sample of your breath. Breath testing is the most commonly utilized
method because it is the least expensive to administer. The scientific
community is sharply divided over the accuracy and reliability of breath
testing procedures. The police do not save the sample of breath
tested. Thus it is not available for re-testing by an independent
laboratory.
Time of
Driving - Not Time of Test
An essential element of the crime of DWI is that the person is
intoxicated at the time of driving. Chemical tests
reflect a person's alcohol concentration at the time of testing. A
person's alcohol concentration at the time of driving may have been
higher, lower or the same. In order to correlate the test result to alcohol
concentration at the time of driving the prosecution may
present expert testimony concerning alcohol concentration at the time of
driving. The process the expert uses to relate the test result back to
the time of driving is known as retrograde extrapolation. However, in
order for the expert to offer an opinion which will be admissible at
trial, the court must find that the expert's opinion will be reliable.
Factors effecting reliability include:
(a) the length of time between the offense and the test(s) administered;
(b) the number
of tests given and the length of time between each test; and
(c) whether,
and if so, to what extent, any individual characteristics of the
defendant were known to the expert. These characteristics and behaviors
might include, but are not limited to
1) weight
and gender
2)
typical drinking
pattern
3) tolerance
for alcohol
4) how
much the person had to drink on the day in question,
5) what
the person drank,
6) the
duration of the drinking spree
7) the
time of the last drink, and
8) how
much, what and when the person ate
Intoxilyzer 5000
Texas uses the Intoxilyzer 5000 to determine breath alcohol concentration. The Intoxilyzer's manufacturer
claims the device works on the principle of Infrared Spectrometry. A
sample of the subject's breath is collected in the device's sample
chamber. At one end of the chamber is a light bulb. At the other end
is a light detector. The machine measures the amount of light that
passes through the chamber when no alcohol is present. This is then
compared with the amount of light passing through the chamber after a
sample of the subject's breath is introduced. In theory, the alcohol in
a breath sample will absorb some of the light. Thus the less light that
passes through a breath sample the higher the concentration of alcohol.
The Intoxilyzer has a computer chip which processes the results of the
test to arrive at a specific alcohol concentration. The calculations
the device performs are unknown as the manufacturer refuses to release
the computer code.
The Intoxilyzer's manufacturer
does not warrant that it is fit to accurately determine
alcohol concentration in human breath. In addition, there is no way to
check the accuracy of results obtained by using this device because the
State refuses to preserve breath specimens for future testing.
Officer
Decides Between Breath, Blood or Urine Test
Under Texas law, the officer determines which type
of sample to request. For example, if the officer requests a breath
sample and you will consent only to a blood test, your license is
subject to suspension as a refusal. However, if you submit to a
chemical test you have the right to have a physician, qualified
technician, chemist, or registered professional nurse take an additional
sample of your blood for analysis. Your request must be made within two
hours of your arrest and the police are not required to transport you
for testing.
Free Consultation - Call Now
A failed breath / blood test does not mean automatic guilt. The
devices and procedures used to determine alcohol concentration are
subject to challenge. Sugar Land DWI Lawyer Anthony R. Segura
offers a free initial consultation to discuss the circumstances of your
case as well as the limitations of breath / blood testing
instrumentation. Call 281-242-7070 to schedule a free meeting with
an experienced Fort Bend County DWI lawyer in Sugar Land, Texas
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