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Blood Test Information
Blood testing is performed by venipuncture
(use of a needle inserted into a vein) in order to extract
a blood sample to be tested for the presence of alcohol
or drugs. The collection of the blood sample may occur in
a number of different circumstances (for example: by a qualified
police phlebotomist at a police station, by a qualified
nurse, doctor or technician at a hospital or clinic, or
by a physician, nurse, or phlebotomist at a doctor's office).
Like most matters relating to DUI / DWI
arrests, issues relating to blood tests are controlled by
state laws. Each state typically has guidelines stating
by whom and how these tests are to be taken, transported,
preserved, secured, analyzed, etc.
Good DUI / DWI trial lawyersknow that fighting
blood tests can be easier than fighting breath tests in
many cases. Blood samples are often difficult to “track”
(i.e., prove the ‘chain of custody’), and a
missing link in the chain may result in acquittal because
there is no reliable sample in the case.
The preferred method of blood analysis (when
looking for alcohol content) is a process called “gas
chromatography” or “GC”. This testing
method utilizes a measuring technique of comparison of a
known “standard” to the subject’s sample.
These standards are typically certified pre-mix solutions,
which have been tested and re-tested for being accurate
and reliable “markers” for the GC device.
If an officer suspects that drugs are all
or part of the impairing substance in your system, most
states permit the officer to demand a blood sample, a urine
sample, or both blood and urine.
The internationally accepted standard for
testing for drugs (other than alcohol) is a “GC-MS”
(gas chromatography, mass spectrophotometry) device. This
piece of equipment is capable of isolating and identifying
a wide range of drugs, including prescription drugs and
illegal (contraband) drugs.
Furthermore, the laboratory will usually
run a quick series of immunoassay tests on a different device
BEFORE running the time-consuming GC-MS tests. These immunoassay
tests are looking for common drugs of abuse, such as opiates,
cannabinoids (marijuana), sedatives, pain killers, etc.
If these immunoassay tests come back NEGATIVE, the lab will
usually report that the sample did not have any type of
drugs in it. If any class of drugs shows POSITIVE, the GC-MS
will be set up to look for common drugs in that “class”
(e.g., sedatives) in the blood sample.
Some states have developed a fairly lax
set of rules for blood testing, whereby testing methods
other than GC and GC-MS can be used.
In most hospitals, alternative testing methods
are often utilized, because they are FASTER. One major difference
in most hospital tests is that these are often done on blood
serum, not the “whole” blood.
Any testing institution that is less reliable
than your state’s crime lab is subject to legal challenge
on even more grounds than those surrounding a state crime
lab challenge. A good DUI / DWI trial attorney will be well
versed on these legal and scientific challenges, if such
second rate, less reliable methods have been used.
Remember: A state crime lab is operated
by people. People make errors. People also change jobs and
move away. Very often, errors in the operation of the GC
or GC-MS instruments, loss of the chain of custody documents
or witnesses, or simply being unable to convince a jury
of the reliability of the test results can result in an
acquittal. Don’t despair about a blood test having
been taken at the time of your DUI / DWI arrest. This may
work to your advantage, if you hire a skilled DUI / DWI
defense lawyer to handle your case.
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