DWI/DUI Facts & Fiction: Urban Myths
by David J. Hanson, Ph.D.
The subject of DWI and DUI is surrounded by
common myths which are corrected here with scientific information
and evidence.
Myth:
Sucking on pennies will lower a person’s BAC reading.
Fact:
Sucking on pennies or other copper has no effect on
alcohol breath tester BAC results.
1 Don’t be a sucker... it makes no cents!
Myth:
“Alcohol on the breath” is a reliable sign of alcohol
consumption and intoxication.
Fact:
Alcohol is actually odorless.... it has no smell. What
people perceive as alcohol on the breath is actually the odor of
things commonly found in alcoholic beverages. The breath of a
person who drinks a non-alcoholic beer will smell the same as that
of a person who has consumed an alcoholic beer.
Research using experienced law enforcement
officers has found that odor strength estimates are unrelated to
blood alcohol concentration (BAC), which ranged in the experiment
from zero to .13 (almost twice the legal limit for driving). The
estimates made by the officers were no more accurate than random
guesses. The researchers concluded that estimates of alcohol on
the breath are unreliable.
2
Myth:
People who abstain from alcohol are "alcohol-free" and
can’t be arrested for DUI.
Fact:
The human body produces its own supply of alcohol
naturally on a continuous basis, 24 hours a day, seven days a
week. It’s called endogenous ethanol production. Therefore, we
always have alcohol in our bodies and in some cases people produce
enough to become legally intoxicated and arrested for DUI.
3
Myth:
A Breathalyzer will clear from suspicion those diabetics
suffering hypoglycemia, whose slurred speech, disorientation,
staggering, drowsiness, poor motor control, and flushed face cause
them to fail field sobriety tests.
Fact:
Hypoglycemia causes acetone in the breath, which the
Breathalyzer will record as alcohol on the breath. Unfortunately,
about one of seven drivers is diabetic and at risk of false arrest
and conviction for DUI/DWI.
4
Myth:
Field sobriety tests, being based on scientific
principles, accurately identify intoxicated drivers.
Fact:
A study conducted by scientists at Clemson University
involved showing police officers videotapes of individuals taking
six common field sobriety tests. The officers were asked to decide
whether suspects were too intoxicated to drive legally. Unknown to
the officers, none of the suspects had a BAC above .000. They had
zero alcohol in their blood. However, in the professional opinion
of the officers, 46% of the completely sober individuals were too
drunk to drive! Therefore, use of field sobriety tests led to
judgments by law enforcement officers that were about as accurate
as flipping a coin.
5
Myth:
Breathalyzers and other breath testers are accurate.
Fact:
There are many, many sources of error in breath testers.
For an explanation of some of them visit
Breath Analyzer Accuracy.
-
Even in the absence of any of these common
problems and under ideal conditions, alcohol breath testers simply
lack precision. Law professor and attorney Lawrence Taylor
explains that “Scientists universally recognize an inherent
error in breath analysis, generally of plus or minus .01%.”
In addition “This has been acknowledged by courts across the
country (see, for example, People v. Campos, 138 Cal.
Rptr. 366 (California); Haynes v. Department of Public Safety,
865 P.2d 753 (Alaska); State v. Boehmer, 613 P.2d 916
(Hawaii), recognizing an even larger .0165% inherent error).
6
This means that under ideal conditions, which is
a highly unlikely situation, a BAC reading of .08 reflects an
actual BAC of anywhere from .07 to .09 or even .065 to .095.
That’s a margin of error of 20 to 30 percent.
Would this be considered a reasonable margin of
error for an accountant, airline pilot, or bank teller? Is this a
reasonable margin of error in court, where guilt should be proved
beyond a reasonable doubt?
Myth:
A person accused of DWI or DWI can demand a jury trial to
contest the results of a BAC estimator machine, with its “ideal
conditions” 20-30 percent margin of error, especially if there are
good reasons to question the accuracy of the results.
Fact:
The right to a jury trial is fundamental to English law
since the Magna Carta and the framers of the United States
Constitution considered is so essential that they included it in
the Bill of Rights. The Sixth Amendment states
"In all criminal prosecutions, the accused
shall enjoy the right to a speedy and public trial, by an
impartial jury of the State and district wherein the crime shall
have been committed..."
The Sixth Amendment provides no exceptions to
this fundamental right to a trial by jury in all criminal
cases.
Although you may have overwhelming evidence of
many types and from many sources that prove your BAC reading is
erroneous and that you are innocent of DWI, many states will deny
you a jury trial.
7
Myth:
Law enforcement officers can’t influence the BAC reading
of a breath-testing machine.
Fact:
Law enforcement officers can and do influence BAC
readings. Law professor and lawyer Lawrence Taylor quotes Dr.
Michael Hlastala, Professor of Physiology, Biophysics and Medicine
at the University of Washington
"By far, the most overlooked error in breath
testing for alcohol is the pattern of breathing.... The
concentration of alcohol changes considerably during the
breath...The first part of the breath, after discarding the dead
space, has an alcohol concentration much lower than the
equivalent BAC. Whereas, the last part of the breath has an
alcohol concentration that is much higher than the equivalent
BAC. The last part of the breath can be over 50% above the
alcohol level....Thus, a breath tester reading of 0.14% taken
from the last part of the breath may indicate that the blood
level is only 0.09%."
8
Professor Taylor explains that
“Many police officers know this. They also
know that if the machine contradicts their judgment that the
person they arrested is intoxicated, they won’t look good. So
when they tell the arrestee to blow into the machine’s
mouthpiece, they’ll yell at him, "Keep breathing! Breathe
harder! Harder!" As Professor Hlastala has found, this ensures
that the breath captured by the machine will be from the bottom
of the lungs, near the alveolar sacs, which will be richest in
alcohol. With the higher alcohol concentration, the machine will
give a higher -- but inaccurate - - reading.”
9
Myth:
Alcohol breath testers measure the concentration of
alcohol in a person’s blood stream (blood alcohol concentration or
BAC).
Fact:
Alcohol breath testers don’t actually measure BAC, which
can only be done by analyzing a sample of blood. They attempt to
measure alcohol in the breath in order to estimate
the concentration of alcohol in the blood. That’s why not all
states permit their use.
-
Given the 20-30 percent inherent margin of
error in alcohol machines under ideal conditions, it would be
wise to avoid being subjected to such an invalid device.
There are good ways to virtually eliminate
being unfairly convicted of impaired or intoxicated driving by
a BAC estimator. One is to choose not to drink, another is to
pace the rate of drinking and follow other tips for
maintaining a low BAC, and another is to select a designated
driver. For specific tips on these practical solutions visit
Breath Analyzer Accuracy.
In reality, alcohol breath testers detect any
chemical compounds that contain the methyl group in its molecular
structure. Unfortunately, there are thousands of such compounds.
Many occur naturally in the human breath or are picked up from
disease; inhaling fumes from gasoline, glue, paint, paint remover,
“new car smell,” celluloid, cleaning fluids, etc.
Breath testers also assume as constants certain
ratios within the human body that actually vary widely from person
to person and within the same person over time. For example, many
breath-testing machines assume a 2,100-to-1 ratio in converting
alcohol in the breath to estimates of alcohol in the blood.
However, this ratio varies from 1,900 to 2,400 among people and
also within a person over time. This variation will lead to false
BAC readings. Some breath analysis machines assume a hematocrit
(cell volume of blood) of 47%. However, hematocrit values range
from 42 to 52% in men and from 37 to 47% in women. A person with a
lower hematocrit will have a falsely high BAC reading. These
machines appear to discriminate against female suspects. For more
visit
Breath Analyzer Accuracy.