By By James O. Harris
Get notified about new articles - join the ExpertPages Mailing List now
When the facts are
against you, argue the law;
When the law is against you, argue the facts.
The above is often quoted
to aspiring attorneys. To successfully argue the facts of a case, the advocate
must understand their contribution to the proximate cause of an issue and the
factors leading to a result. This is one reason there are expert witnesses.
Few trials would be complete without expert testimony.
The ultimate goal of
a traffic accident investigation or reconstruction is to determine the events
of the accident, or what caused the accident. There are many publications available
on the subject of cause as cause is the heart of the issue at trial. The subject
matter can be complex since there are so many circumstances and factors that
must be considered in a cause analysis. There is also the matter of what does
One pitfall a
reconstructionist, or an attorney, faces is defining "cause." As most of the
reconstructionist's work involves the legal profession, a common understanding
of the legal term will be useful to prevent confusion.
Cause in law
is different from cause in the rest of the world. In the eyes of the courts,
cause is an issue of policy and not an instrument of factual analysis. The issue
for the court is whether, as a policy decision, a defendant should be held liable
for injuries or damages. In a traffic accident case, the resolution of that
issue depends on whether the crash was a foreseeable result of a defendant's
negligence or willful act.
This sounds contrary
to that which is taught to police officers, traffic homicide investigators and
accident reconstructionists. The work of the accident investigator is preliminary
to the analysis performed by the jury. The jury is bound to consider the evidence
and will consider the quality and completeness of the analyst's presentation
in coming to a conclusion. Put another way, the juror is not constrained to
the same principles of factual analysis as is the investigator.
hold that any event that was a substantial factor in causing a harmful event
is a legally relevant proximate cause of the event even if other things were
also substantial factors and therefore concurring proximate causes of that event.
This does not mean a law violation must be construed as a causative factor in
an accident. For example, a vehicle's registration may have expired but this
would not be relative to the vehicle being involved in a collision although
it is a violation. Many traffic laws exist solely to govern the safe movement
of traffic on the highways; stop signs, lane division, speed limits, etc., and
may concur with an accident factor that existed. For the police officer, it
is convenient to match a law violation with a "cause" but this practice often
results in errors as it tends to ignore other existing factors that may have
been present and were equally contributing to an accident.
law violation that is considered a modifier of the human factor is intoxication.
Assume a vehicle is stopped at a stop sign. The driver is legally intoxicated.
His car is struck in the rear end by another vehicle. The fact that the driver
of the lead vehicle is intoxicated is not a factor in this accident but the
law violation is present. His performance did not contribute to the event. When
determining intoxication as a factor in an accident, the effect of the level
of intoxication in the human performance factor needs to be quantified. For
example, if a driver was not intoxicated, would the accident still have occurred?
the courtroom and in factual analysis, cause is whatever is required to produce
a result. A case normally consists of a combination of factors, circumstances
or conditions that must be present to produce the result. Consider a cigarette
lighter. For a flame to be produced, there must be fuel, a flint, a striking
surface this is free of moisture and someone to actuate the mechanism. Take
out any of these circumstances and the lighter will not produce a flame. Not
only must these circumstances be present, they must be present simultaneously.
In this example, it is a simple matter to find one circumstance that must be
present to produce the result, such as the fuel, but in other situations the
factors may be difficult to identify.
or conditions exist simultaneously, the degree of each condition may be important.
Consider two drivers, Smith and Jones. Smith, with better visual acuity, can
see better in dim light than Jones. Driving along a dark country road, without
headlights, neither driver can see a pedestrian walking along the side of the
road. With high beam headlights, both Smith and Jones can see the pedestrian.
With low beam headlights, Smith can see the pedestrian but not Jones. High beams
allow Jones, even with his poorer visual capacity, to see the pedestrian as
can Smith. But Jones cannot see as well as Smith under the same circumstances
even though the environmental conditions were identical. An analysis of an accident
involving Jones and the pedestrian would include trying to determine whether
it was due to poor visual acuity or insufficient lighting conditions. If three
or more conditions interrelate, the evaluation of the circumstances becomes
considerably more complex.
events are closely interrelated when considering accident factors. Some may
be obvious and others difficult to determine. If a large truck is involved in
an accident and the fuel tank is ruptured, the cause of the rupture and resulting
fuel spill, is readily determined. If the fuel was to ignite, the cause of the
ignition may be indeterminate but subject to speculation.
A "factor" is a circumstance
contributing to a result. Without this factor, the result would not exist but
the factor alone is an element that, by itself, cannot produce the result. The
term "contributing factor" is meaningless if this definition is accepted. A
factor must be contributing if it is present otherwise it is not a factor. The
term "primary factor" is sometimes used by experts to indicate a factor that
was strong in its contribution to the accident. This is misleading as there
can be no one factor more important than any other if all factors must have
been present to produce a result. No factor can be secondary, or less important
than another if all are required for the result. Like the links of a chain,
all must be present and none is more or less necessary than the other.
Consider a road
with a sharp curve. One year, 10,000 cars safely negotiate the curve. During
the same year, 50 cars failed to negotiate the curve and crashed. What was the
cause of the accidents? If it is accepted that the sharp curve was the cause,
then all the cars traveling on this road would have had an accident. It may
well be a factor, but certainly not the sole circumstance in existence that
precipitated the accidents. A combination of factors, speed, driver capability,
vehicle condition and environmental conditions all come into play.
In a two car
head-on collision, multiple factors again come into focus. Why was one driver
left of center? Was it a problem of perception? Or attitude? Why did the other
driver not take evasive action? Did a passenger not warn the driver of the impending
hazard? Is there road design defect? A failure to properly mark, sign or maintain
the road? Obviously, many questions are not addressed and will not be answered
by a police officer filling in blocks on a standard accident report form.
Actors fall into
three primary areas: road, vehicle and human. Each area is subject to a variety
of modifiers. For instance, road factors include, but are not limited to lighting,
view obstructions, recognizability, signs, signals, surface character, dimensions
and protective devices. All factors are subject to modification by outside influences
such as the road surface that becomes slick from rainfall. Modifying each of
the listed road factors are weather, lighting, roadside devices, activities,
surface deposits, damage, deterioration and age.
factors include equipment condition, view obstructions, distractions, instruments,
signaling devices, control sensation, comfort, automatic controls and devices,
weight, performance, dimensions and stability. Vehicle speed, as a factor, must
exist. If neither vehicle had any speed, there could not have been a collision.
are without doubt the most complex and difficult to isolate as they are almost
all very temporary in nature. What existed at the time of the accident may not
exist moments later. Consider sensory capabilities, knowledge, judgment, attitude,
alertness, health, driving skill, age, customs, habits, weight, strength and
freedom of movement. Of these, the emotional factors are the greatest variable
attributes and the most difficult to identify. They are also subject to the
most modification with the least remaining evidence.
factors may be considered when dealing with cause analysis although they are
seldom of significance to the investigator on a single accident case. Remote
condition factors may involve a changing cultural climate in which the factors
and their modifiers form. This includes moral influences, religion, beliefs,
legal influence and values on vehicle designers, highway engineers, drivers
In most reconstructions
preformed for civil litigation, collision avoidance is an issue. Much of this
analysis falls under a category of predisposing circumstances. Some of these
circumstances can be controlled by the individual. In small amounts, alcohol
in the bloodstream may have little effect on a driver's capabilities. In larger
quantities, the effect can be dramatic and greatly increase the chances of an
accident. A driver may be exposed to a predisposing circumstance, such as consuming
moderate amounts of alcohol before driving for many years and never have an
accident. It is only when this circumstance is combined with other circumstances
that the full effect of the predisposing circumstance becomes evident. Other
predisposing circumstances, like driving in a rainstorm, can be avoided by trip
the factors that were present in any single accident would be a monumental undertaking.
With human foibles, none will ever be complete or accurate. There are simply
too many factors, modifiers and circumstances present that may have disappeared
long before the investigator becomes involved. Other circumstances may simply
never be revealed, or realized, by the parties involved. The examination of
many accidents at one location may reveal a single, unique circumstance common
to all accidents there. This is useful in isolating a factor not readily observable
in a single case.
test for proximate cause is the accident must be the natural and probable result
of a negligent act or omission and be of such a character as an ordinarily prudent
person ought to have foreseen it as likely to occur as a result of the action.
It is not essential that the person charged with the negligence should have
foreseen the precise injury from his action.
definition makes the work of the accident analyst and advocate easier in that
not all the factors present in an accident may be sufficiently relevant to the
cause for consideration. Mere presence is insufficient, it must have in some
significant way contributed to the result. As such, there are several factors
that are routinely identified as being substantially contributing and others
are accepted or implied as being present and normally expected. In a case where
a vehicle falls or flips, gravity is a factor and its existence is accepted.
This does not relieve the analyst of the responsibility of being aware of the
presence of additional factors because in any case any one of them may be critical
in determining proximate cause.
a good understanding of the relationships of accident factors, circumstances
and modifiers, and sufficient data, an accident can be analyzed, causation determined
and the conclusions effectively presented.
O. Harris. Email: email@example.com
Reprinted with permission from James Harris.