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Driving. Intoxication is not enough: the prosecution must also
prove that the defendant was driving. This may be difficult if,
as in the case of some accidents, there are no witnesses to his
being the driver of the vehicle. |
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Probable cause. Evidence will be suppressed if the officer did
not have legal cause to (a) stop, (b) detain, and (c) arrest.
Sobriety roadblocks present particularly complex issues.
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Miranda. Incriminating statements may be suppressed if warnings
were not given at the appropriate time. |
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Implied consent warnings. If the officer did not advise you of
the consequences of refusing to take a chemical test, or gave it
incorrectly, in some states this may invalidate a DMV license
suspension based upon a refusal to provide a breath/blood
sample. |
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"Under
the influence". The officer's observations and opinions as to
intoxication can be questioned -- the circumstances under which
the field sobriety tests were given, for example, or the
subjective (and predisposed) nature of what the officer
considers as "failing". Too, witnesses can testify that you
appeared to be sober. |
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Blood-alcohol concentration. There exists a wide range of
potential problems with blood, breath or urine testing.
"Non-specific" analysis, for example: most breath machines will
register many chemical compounds found on the human breath as
alcohol. And breath machines assume a 2100-to-1 ratio in
converting alcohol in the breath into alcohol in the blood; in
fact, this ratio varies widely from person to person (and within
a person from one moment to another). Radio frequency
interference can result in inaccurate readings. These and other
defects in analysis can be brought out in cross-examination of
the state's expert witness, and/or the defense can hire its own
forensic chemist. |
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Testing during the absorptive phase. The blood, breath or urine
test will be unreliable if done while you are still actively
absorbing alcohol (it takes 30 minutes to three hours to
complete absorption; this can be delayed if food is present in
the stomach). Thus, drinking "one for the road" can cause
inaccurate test results. |
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Retrograde extrapolation. This refers to the requirement that
the BAC be "related back" in time from the test to the driving.
Again, a number of complex physiological problems are involved
here. |
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Regulation of blood-alcohol testing. The prosecution must prove
that the blood, breath or urine test complied with state
requirements as to calibration, maintenance, etc. |
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License suspension hearings. A number of issues can be raised in
the context of an administrative hearing before the state's
department of motor vehicles. |