Studies show that almost 40% of crash reports involve drunk
or impaired driving. However, these cases are difficult to prove as many prosecutors
are not equipped with the technical knowledge necessary to prove the elements
of the offense. This makes expert testimony, crash reconstructionists, and
mathematical or scientific proof and analysis essential.
In this short blog, David Serna discusses what prosecutors
should know and look for when investigating a case on impaired driving.
The Phases of a Crash
A car crash occurs in three phases: pre-impact, engagement,
and post-impact. These phases are further broken down into several events:
point of first possible perception, point of actual perception, point of no
escape, point of operator action, point of impact, post-impact trajectory, and
final rest position. However, not all car crashes involve these events. The
sequence of these events varies and is a case-to-case basis.
Analysis of the Evidence
The more evidence prosecution has, the fewer loopholes
defense can use. This is true for all criminal cases. The defense will most
likely use expert testimony to rebut the evidence presented by the prosecutor.
David Serna says that prosecutors must, before going to
trial, learn some of the following crash reconstruction fundamentals: analysis
of the friction marks left by tires, drag factor, crush analysis, momentum
analysis, time-distance analysis, speed from event data records.
Common Defenses used in Impaired Driving
Defense usually attempts to decrease the value of the drag
factor. Since the prosecutor relies heavily on mathematical values and
reconstruction methods, the defense usually claims that the drag factor and the
weight of the vehicle are incorrect, post-impact vehicle rotation was not taken
into consideration, and the approach angles were not determined or
investigated.
Prosecutors must anticipate these defenses. For more
information on criminal law, defense, and prosecution follow blogs by David
Serna.
