As you may know, when you are charged with a crime, you have no obligation
to present evidence in your own defense. This is known as the presumption
of innocence, and it is the cornerstone of our criminal justice system.
However, in some instances, it may be beneficial to present evidence to
a jury that can help create a reasonable doubt. This is true in cases
that involve scientific evidence, such as
(breath test results), sexual battery (DNA analysis), and
Accused persons may retain expert witnesses to testify at trial. An expert
witness is skilled in a particular field and can provide invaluable insight
that may rebut a claim made by the State.
For instance, if you are charged with DUI and the State introduces evidence
that your breath-alcohol content was above the legal limit of .08, you
may present expert testimony to show that the Intoxilyzer machine was
not functioning properly on the date of the breath test.
Experts in breath testing may be former police officers who may have held
breath test operator permits. Given their level of training and experience,
it is possible that their testimony can help to create doubt in the minds
of the jurors as to whether the supposed breath reading is accurate.
Also in DUI cases, toxicologists can be helpful to the defense in showing
that an accused person was not legally impaired at the time of the arrest.
This is because alcohol is absorbed and metabolized by the body at difference
rates. If you are driving at 5:00 p.m. and you are pulled over, you may
only be at a .05 at that point. If your body is the absorbtion phase,
you may blow a .09 when you submit to the breath test 90 minutes later.
The law prohibits
driving while impaired. Your blood-alcohol content cannot be at a .08 or higher
at the time when you are driving the car. A toxicologist uses a scientific
method known as extrapolation to demonstrate what your true blood-alcohol
content would have been at the time you were driving.
Experts may also be helpful in cases with physical evidence, such as DNA
or fingerprints. This is because experts may be able to show that the
DNA sample was tainted, which could yield false results. A fingerprint
expert can demonstrate that the prints were not lifted properly, thus
were smudged and could not be used for comparison.
An expert witness should be educated in their field. They should be respected
and unbiased. That is, you should consult with your
Miami-Dade County criminal defense attorney when selecting an expert witness. You should pick somebody who does not
have a reputation as a "defense expert." That is, an expert
whose income is dependent upon being hired by criminal defense attorneys.
In turn, these experts will almost always testify favorably for the defense.
Your expert witness should be respected by the State Attorney's Office
as well as the defense bar. He or she should have no professional discipline
matters on their record. They should be published (if applicable) and
have advanced degrees. If the expert is not necessarily a scientific expert,
they should have adequate professional experience and accolades. The expert
should be a member of a professional organization.
Expert witnesses can be costly, so make sure that your budget allows you
to retain one. If you cannot afford an expert, your attorney may be able
to file a motion asking the Court to have the State pay the witnesses
fees. Your not likely to get the State to pay for your $500-an-hour DUI
expert, but they may pay for mitigation specialists, such as mental health
professionals, for purposes of a downward departure hearing.
Not all cases require expert testimony. But every now and again, it is
not a bad idea to give a jury an intelligent opinion which may impact
The Law Offices of Eric M. Matheny, P.A. is a
Miami-Dade County criminal defense law firm representing clients in Miami-Dade County and Broward County.
Call today for a consultation.