Evidence of BAC in Utah DUI Trial
Is a prosecutor required to present scientific evidence of
BAC to prove DUI?
A prosecutor may request that a
trial judge give a jury instruction
that explains that
the prosecutor is not required to introduce "scientific evidence" in
order to meet the burden of proving the case beyond a reasonable doubt.
These instructions are sometimes referred to informally as a "CSI"
instruction, and are designed to try to counteract the effect that
modern television crime dramas have had on juror's expectations.

A
CSI instruction may be a valid statement of law and may make sense in
some cases. For example, in a bike
theft case we would not expect the
police to swab for touch DNA or take fingerprints . . . when
the
officer personally saw the defendant riding the bike away from the bike
rack as the owner yelled "stop thief!" Police departments have limited
scientific resources, and should not be required to expend those
resources in cases where scientific evidence is unnecessary. But
in a
DUI case, the legislature has enacted a statute that
begs for scientific evidence.
What evidence is required to prove a DUI?
A charge under Utah Code 41-6a-502 provides alternative methods by
which a prosecutor can prove a DUI. One method requires no evidence of
a specific determinable BAC (blood or breath alcohol concentration); it
requires only proof that the person was impaired by alcohol or drugs to
a degree that the person was not able to safely operate a vehicle. A
prosecutor usually attempts to prove this impairment by introducing
evidence of a bad driving pattern (swerving, failing to stay in one
lane, etc.) or by evidence of an actual accident.
A more common method of proving DUI is to prove a BAC of 0.05 or
greater. (NOTE - As of January 1, 2019, Utah's per se DUI limit was
changed from 0.08 to 0.05.) This method puts the prosecutor at an
advantage, because no
proof of any actual impairment is required. Instead, the DUI charge can
be supported based just on evidence of a BAC of 0.05 or greater. But
proof of BAC requires scientific testing.
Is an estimate of BAC sufficient to prove DUI?
Police officers are trained in many areas of investigation that involve processes of
estimation. An officer may receive training in estimating the speed of
a moving vehicle, based on visual observations of the vehicle as
compared with a stationary background or as compared to the officer's
own speed. An officer may be trained in estimating the weight of
package of marijuana, based on the volume or heft of the package.
But there is no way to make an accurate visual estimate of BAC, no way
to visually analyze a blood sample to determine BAC, and no way to
accurately estimate BAC based merely on the odor of alcohol on a
person's breath. A person who "holds their alcohol well" might easily
have a BAC of more than twice the legal limit yet still not show
immediately obvious signs of impairment. Yet another person with a much
lower BAC could show much greater visual indicators of intoxication.
Determining the actual blood or breath alcohol level requires scientific testing to get real
numbers. So asking for scientific evidence in a DUI trial is not at all unreasonable.
What about FST's? Can they support proof of BAC in a DUI
trial?
The NHTSA standardized
field sobriety tests (FST's like the
walk-and-turn, one-legged stand, and horizontal gaze nystagmus) can be
used to support probable cause to arrest for DUI. But these FST's
support only a probability that a person may be above a certain BAC.
There are conditions and situations that can cause a 100% sober
individual to still fail the FST's. Failure on the FST's, by itself, is
not sufficient to establish proof beyond a reasonable doubt for a DUI
conviction. But a person's performance on the FST's can be considered by a jury or judge.
Is a CSI-type instruction appropriate in a DUI trial?
Courts give the CSI instruction
to help jurors understand the difference between fictional television
drama and the real world. In the real world, police don't swab every
surface for DNA; police don't bring a black light to every hotel room crime
scene; police don't do fiber analysis on every piece of clothing; and
computer photo enhancement usually doesn't produce a legible license
plate.
But in a DUI case, police officers can and regularly do
administer breath tests or take blood or urine samples for the lab to
test. And even when a suspect refuses to submit to the test or to have
a sample taken, police officers can and regularly do get warrants so
that they can take whatever kind of sample they need to take in order
to properly do their job.
The CSI instruction may be just fine
for helping juries understand the difference between Hollywood and
reality. But a CSI instruction should not be used to excuse the police
from failing to do their jobs. Sure, a prosecutor can proceed on the
argument that, regardless of BAC, the person was not able to safely
operate the vehicle. But the judge should not instruct the jury in a
way that essentially gives the police a pass for not bothering to get a
sample to test.
Finding a DUI Attorney in Utah

If
you are facing prosecution for DUI,
driving with measurable metabolite, or other
alcohol- or
drug-related charges in Utah, it is vital that
you consult with and obtain the assistance of an
experienced criminal
defense attorney. The Utah criminal justice system is complex and the
penalties for DUI and related charges can be severe. The right defense
strategy
and the right
criminal defense attorney
can make all the difference.
Contact us today to
see how we can help you.