Types of Evidence Useful
for Understanding the JFK Assassination
(December 2000)
Understanding the JFK assassination depends on
one’s ability to extract the few valuable pieces of evidence from the large
mass of unhelpful evidence. This requires us to understand the various types of evidence,
how evidence is used in the legal system, and the ways in which evidence may be
used by students of the assassination. This essay provides a brief introduction
to the basic types of evidence and their characteristics. It puts formal legal
definitions into readable English and extracts the most important ideas
from them. (Surprisingly, the law uses English poorly, and is full of vague
terms and words with multiple meanings. While this ambiguity may give lawyers,
judges, and the law the flexibility they consider important, most of the time it
only confuses the rest of
us.)
The legal system uses a wide variety of terms
to describe evidence, many of which deal with minor or specialized aspects of
evidence that are irrelevant to the assassination. Worse, a number of terms
overlap or duplicate one another. Different sources often
offer conflicting definitions. To the lay person, this can be very
confusing. Luckily, we as critical thinkers in the JFK case need only concern
ourselves with major distinctions.
Definitions and properties
What is evidence?
Here are some typical legal
definitions of evidence: (1) any species of proof, or probative matter, legally
presented at the trial of an issue, by the act of the parties and through the
medium of witnesses, records, documents, exhibits, concrete objects, etc., for
the purpose of inducing belief in the minds of the court or jury as to their
contention; (2) testimony, writings, or material objects offered in proof of an
alleged fact or proposition; (3) that probative material, legally received, by
which the tribunal may be lawfully persuaded of the truth or falsity of a fact
in issue; (4) all the means by which any alleged matter of fact, the truth of
which is submitted to investigation at judicial trial, is established or
disproved.
In other words, evidence includes all the ways
by which we try to prove allegations.
Ideas versus objects
Evidence can be ideas or objects.
Ideas, or human interpretation of information relevant to the allegation in
question, can be delivered orally, or testified to, by a witness under oath, as testimonial evidence. Testimonial evidence can
also be given in written form, via affidavits or depositions.
Ideas from nonwitnesses can also be presented
in written form, generally as documents of various kinds. Such evidence is
called documentary evidence, which can be defined as ideas represented on
material objects such as deeds, wills, titles, letters, contracts, receipts,
X-ray plates, and so forth.
Evidence can also be presented by means of
objects, sometimes collectively referred to as material objects, physical
objects, or "probative material." Such evidence is called demonstrative
evidence or real evidence. Demonstrative evidence is seen, heard,
etc., directly rather than being described by a witness. By illustrating some
aspect of verbal testimony, it can help the jury understand the crime.
Demonstrative evidence does not directly address the question of guilt, however. Examples
of demonstrative or real evidence are guns, contracts, maps, diagrams,
photographs, models, charts, medical illustrations, and X-rays.
Thus, evidence can be said to encompass
testimony, writings, and physical objects.
Relation to the allegation
Evidence is either direct or indirect.
As its name suggests, direct evidence relates immediately to the
allegation being tested. If the direct evidence is true, the allegation is
established. Black’s Law Dictionary defines direct evidence in these ways,
among others: "Evidence, which if believed, proves existence of fact in
issue without inference or presumption," and "Evidence…which in
itself, if true, conclusively establishes [a] fact." (As noted in
"Using important words precisely," fact should not be used in
this way because it refers to something not yet established.) An example of direct evidence would be the surveillance
video of a person robbing a convenience store. Another piece of direct
evidence would be a witness who saw a person steal a car. Direct evidence in the
JFK assassination would be the testimony of a witness who saw someone fire one
or more shots from the Texas School Book Depository.
In contrast, indirect (circumstantial)
evidence does not bear immediately on the allegation, but rather on
something related to it. From the related fact(s), the existence of
the allegation in question can be inferred (but not proved). Indirect evidence is normally
the strongest collectively, when multiple pieces combine to strengthen
a particular conclusion. Indirect evidence is sometimes called collateral
circumstances.
At first glance, direct evidence would seem to
be stronger than indirect, because the former can prove the question
whereas the latter requires inference (deduction or induction). And yet, the
opposite can be true—circumstantial inference can be correct if its data are
correct and its patterns of reasoning are sound, whereas a conclusion derived
from direct evidence can be wrong if the evidence is flawed. For these reasons,
the law generally does not favor direct or indirect evidence over the other. A
judge or jury considers evidence of all types.
Evidence that is indirect to the crime is direct to some
facet of the crime. For example, an audio tape of two conspirators planning a
crime is direct to the conspiracy but indirect to the crime itself because it
cannot prove that the conspirators actually committed the crime. A receipt for
purchasing a gun is direct evidence that a certain person owned the gun but
indirect that he used it in committing a crime. The great majority of evidence
considered in typical trials is indirect to the crime itself.
Strength of evidence
The law uses two archaic terms for strength of evidence, neither of which
are helpful for the assassination. The stronger type is called mathematical. According to Black, evidence is mathematical
if it "establishes its conclusions with absolute necessity and
certainty."
Moral evidence
is "highly probable" or "highly persuasive," i.e., weaker. Examples include arguments from analogy or induction, experience of the ordinary
course of nature or the sequence of events, and the testimony of men. (Sorry,
you women—this last phrase comes directly from the law.)
But what about evidence that is weaker than
"highly probable" or "highly persuasive"? The law seems to
have no consistent terms for this category. For the
purposes of the JFK assassination, we may describe the three common strengths of
evidence as conclusive (or strong), persuasive, and weak
(or something similar). These would correspond to probabilities of roughly 95%
and greater, 75–95%, and less than 75%.
Reliability of evidence
One of the most
important characteristics of evidence is its reliability. This property is
particularly germane to understanding the JFK assassination, where much
questionable evidence has been produced and intermingled with the solid evidence.
Unfortunately, the law provides no systematic way other than the courtroom to
distinguish good evidence from bad. Fortunately, however, disciplines outside
the law do.
Determining the reliability of a piece of
evidence is a two-step process. The first step, often neglected but exceedingly
helpful, is to assess the testability of the evidence. If the evidence
cannot be tested rigorously and objectively, it is useless because we can never
know whether it is right or wrong. While this sounds like a truism, it is
actually an enlightening principle that when used consistently can bring order
to large masses of evidence. The second step is to determine the correctness,
or accuracy, of the evidence. Thus to determine the reliability of evidence, we
first decide whether it can be meaningfully tested, and then, if the answer
is positive, we try to validate it.
Testability
Many ideas or pieces of evidence are inherently untestable, that is,
they are of a type whose correctness cannot be determined objectively. The
eminent philosopher of science Sir Karl Popper has discussed at length this property of
evidence, which he calls falsifiability. (See his essay "Science,
pseudo-science, and falsifiability.") Most people feel intuitively that
"testable evidence" is something like
"scientific" data, in distinction to untestable evidence, which would
come from "unscientific" sources. The precise definition is quite
straightforward, however: testable evidence is that which has a concrete
object (which can be a photo, a graph, a table of data, etc.) and a
description or interpretation of the meaning of that object written by a person
capable of understanding it. (In a courtroom, the person would be a sworn
witness, often an expert.) The physical nature of the object allows the
statement to be checked independently and objectively by others (i.e., to be falsified). This opportunity for validation forms the core of the first step in
determining reliability.
For simplicity, then, let us define
testability as the property of being objectively falsifiable, or simply physical. Any
evidence that is not testable is automatically weak, i.e., it has
little or no probative value. For example, evidence based on someone’s word is untestable and therefore unreliable and
weak. But since testabililty is only the first step toward reliability, testable
evidence is not automatically reliable.
Examples of testable evidence
Testable evidence includes everything physical. For the
JFK assassination this means medical
(e.g., X-rays and autopsy photographs), classical ballistics (e.g. tracing bullets
and casings to weapons by matching lines and markings), applying physics to
ballistics (as in the Z-film), wound ballistics (e.g. using shapes, sizes, and
markings of wounds to determine whether of entrance or exit; determining
direction of bullets from beveling and coning), hair and fiber analysis,
fingerprints, chemical analysis (emission spectrography, NAA, and other modern
techniques), and the more-modern DNA analysis. Note that every one of these
types of evidence combines a physical object with an expert’s interpretation of it.
The next few paragraphs give some brief examples of each of these
in the JFK case.
Ballistic analysis. By comparing the markings on
the three largest fragments of bullets found in the limousine and at Parkland
Hospital with various rifles, FBI investigators were able to determine that they
had all been fired from Oswald's rifle to the exclusion of all other rifles.
Similar results were found for the three cartridge cases found on the sixth
floor of the Depository.
Wound-ballistic analysis. The physicians who
examined the bullet wounds to Kennedy and Connally tried to categorize them as
entrance or exit wounds from their properties. They got most of them right. The
team at Parkland misidentified the tiny hole in the throat as an entrance wound,
however. They were right that it looked like an entrance wound, although
it was really the exit wound from the body shot that entered Kennedy's upper
back/lower neck region. The Parkland personnel were handicapped because (a) they
did not know of the back wound, and (b) they soon destroyed the wound by using
it as a starting point for their tracheotomy.
Chemical analysis. The set of lead fragments from
the bullets was analyzed twice for trace elements, once by the FBI in 1964 and
later by the HSCA in 1977. When properly interpreted, both sets of results offer
very strong evidence (but not proof) that only two bullets, both from a
Mannlicher-Carcano rifle, hit Kennedy and Connally. When combined with the
ballistic evidence for the large fragments, they show that the
Mannlicher-Carcano in question was in fact Lee Harvey Oswald's. Thus, all the
fragments recovered that were big enough to analyze came from two bullets fired
from his rifle that day.
Analysis of motions by physics. The motions of
Kennedy's head and body after the fatal bullet hit his head are recorded on the
Zapruder film. When analyzed carefully in terms of conservation of momentum and
energy, the number of bullets hitting his head and their general direction of
origin can be determined nearly conclusively.
Forensic pathology. The documentary records from
JFK's autopsy include notes, reports, diagrams, photographs, and X-rays. All are
available for qualified physicians to study and interpret.
Hair and fiber analysis. The Warren Report
describes how, for example, the fibers caught on Oswald's rifle were compared
with those of the shirt he was wearing that day.
Fingerprint analysis. The Dallas Police Department
and the FBI lifted various fingerprints and palmprints from the rifle, the boxes
on the sixth floor of the TSBD, and so on. Some were Oswald's; some remained
unidentified.
Analysis of documents. The Warren Report describes
how various documents from Oswald's possession were checked for accuracy. Some
were found to be fakes, such as his ID cards. Others were found to contain alias
signatures in his handwriting, such as the records of ordering and receiving his
pistol and his rifle.
Correctness
Once a piece of physical evidence has been identified, it
still must be tested before it may be
considered reliable. There are various ways to test
evidence. One is to examine whether it agrees with other evidence that has
already been validated. Another is to examine the consequences (predictions)
of the evidence and see whether they correspond to reality. A third is to
gather new data to test the piece of evidence. This also can be a long job, but
it is truly worth the effort. (For an organized series of steps for checking
evidence, see "A critical method for the JFK assassination" in the
essay "A critical method for understanding the JFK assassination.")
Examples of untestable evidence
Numerous as the examples of testable evidence listed above are,
their numbers are dwarfed by the huge mass of evidence that is untestable. (See "Shadings of
eyewitness testimony.") These types of weak evidence includes testimony
of eyewitnesses at the scene (a vast record indeed); some undeterminable
fraction of Marina Oswald's testimony; recollections of the medical personnel
who attended Kennedy in the emergency room at Parkland Hospital (much discussed
of late); recollections of the staff at Parkland Hospital; recollections of the
ambulance personnel; recollections of the autopsy technicians in Bethesda
Memorial Naval Hospital; deathbed confessions concerning who might have ordered
Kennedy killed; speculations about who else might have wanted him killed and
why; views stated by members of the Kennedy family and others close to the
assassination; reports of seeing Oswald in various places (Clinton, LA?) or with
various people (with Ruby and the Carousel Club; having an office at 544 Camp
Street in New Orleans; meeting with "Maurice Bishop"; test-driving a
car in Dallas; etc.); entire books written by people confessing to be
conspirators or in league with the actual conspirators (such as Robert Morrow's
"Betrayal"); and so on. You get the picture. Many books about the
assassination have been based virtually completely on this weak evidence.
Consequently, they must all be dismissed outright as unverifiable, therefore
uncertain, and therefore useless in practice.
Purging the unreliable evidence
Welcome to the frustrating world of the JFK assassination!
What do we do when we can't trust most of the evidence? We follow steps 3a,b of the pattern of critical thinking offered in "A
critical method for understanding the JFK assassination." First we
divide the available evidence into strong and weak, where strong
effectively means physical. Then we eliminate all the weak evidence and proceed with the
physical.
Step 3 is perhaps the most distinctive of the nine steps in
this pattern of critical thinking. It is controversial among JFK researchers
because it goes against the grain of so much of their research. And yet it is
fully justified from the standpoints of logic, common sense, and tradition. It
offers the fastest and most efficient path to delimiting the answer. It offers
the most realistic assessment of the quality and quantity of the available
evidence. It offers an immediate sense of how close to an answer we are likely
to get. (See the essay on asking the
right first question.) Anyone who does not
follow this method is going against logic, common sense, and centuries of
critical tradition, and is guaranteeing an uncertain, if not wrong, answer. Seen
in this light, there is no choice.
Of course, clearing out bad data will significantly
restrict the number of conclusions we will be able to draw. It will also
restrict the number of topics we will be able to consider. Many
JFK researchers consider this penalty too harsh to bear. I say the opposite—I
consider it a relief to have settled this all-important question. The last thing
I want is to be wrong about any part of the assassination. Far better to remain
silent about some part than to be wrong about it.
It is very
important to be conservative here—better to err on the side of eliminating
some data that are correct than to let in any data that are wrong. The moment we
include any data of dubious reliability, we can no longer be sure that any
subsequent conclusions are correct. Our goal needs to be much like the
physician's "First, do no harm." I see no way to avoid these harsh
measures if we really want to get the answer.
But this approach is really nothing new—we do the same in
all matters of importance in our daily lives. When we go looking for a new car,
for example, we want to be sure that we are provided with the correct
information. If a salesman misleads us or offers incorrect information, we go
somewhere else immediately. When we set out to buy a house, we often get it
inspected so that we know the truth about it. Why then should we be any less
rigorous with the JFK assassination?
Surprisingly few JFK researchers treat their evidence like
this. They let in anything and everything, and hope that somehow the weaker
information will be sorted out in the wash. Even if they give initial lip
service to hard evidence, they don't follow it in practice. They just take it
all in and arbitrarily emphasize what seems best to them. Those practices guarantee disaster. The link between evidence
and conclusions cannot be beaten—include unreliable evidence and your
conclusions will be unreliable. I submit that no one among us wants that.
Then why do JFK researchers insist on including unreliable
data? It clearly is an irrational act. We had best leave this question until
later in the course, for the answers are not pretty.