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2.
Formulating Hypotheses
To reiterate, hypothesis testing is the cornerstone of classical science, and one
operational model for forensic science. This would seem to obligate the
scientist to state a null hypothesis that can be tested and potentially falsified.
Interestingly, in forensic science, the hypothesis being tested is rarely expli-
cated. We believe that it should be. Carefully formulating alternative hypoth-
eses can save countless hours on useless analyses and prevent immeasurable
aggravation in attempting to interpret an analysis that might have been
organized differently.
Probably the biggest favor most analysts could do for themselves and our
profession would be to start formulating and explicating the scientific
hypotheses that they will be testing with their analyses. To formulate a useful
scientific hypothesis to test, the analyst must have some idea of the circum-
stances of the crime. This brings us to one of the more contentious points
of argument between lawyers and scientists. How much should an analyst
know about a case, and does that knowledge precipitate bias?
 
3.
How Much Should an Analyst Know?
The singular act of laboratory analysis or comparison is set against the greater
backdrop of the events and decisions surrounding it. In many ways, the analysis
itself can have less effect on the final outcome of a case than the decisions leading
to which evidence is tested, how it is tested, and how the results are interpreted
and communicated. Typically, the analyst knows something about the history
of the evidence up until the time it enters the laboratory, and will interpret the
results based on that history. Forensic scientists are generally familiar with the
need to interpret evidence in the context of the history of the sample prior to
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Good Forensic Practice — Obligations of the Analyst
249
its collection and preservation. But before the results are interpreted, and even
before any analysis occurs, the criminalist must define the relevant questions.
The more the analyst knows about the case, the better she can direct and refine
the questions so that the answers are both useful and relevant.
The argument, made mostly by attorneys, against the analyst knowing the
circumstances of a case, is that such knowledge may introduce subconscious,
or worse yet malicious, bias, leading to prejudiced interpretation of the
results. Superficially, this would seem to be a credible thesis. However, we
believe that the advantages gained as a result of an informed analysis sub-
stantially outweigh the concerns. Furthermore, a series of checks and balances
can and should be employed to ensure that alternate explanations for the
data are duly considered. Moreover, we submit that bias is most likely to
enter a case and do the most damage at the level of the question being asked,
rather than in the interpretation of results. Because the hypotheses (however
unconscious), and the assumptions that generate the questions, virtually
always initiate with law enforcement, the criminalist is indeed in an excellent
position to question accepted notions about a case and provide counterpoint
suggestions.
Criminalists are experts in the possibilities inherent in physical evidence
and also in the limitations of the various tests employed. Because of this
specialized knowledge, we are in a unique position to offer the criminal justice
system guidance on the best way to elicit information about a disputed or
unknown fact. One of the greatest unrecognized contributions that a crim-
inalist can provide is in framing the correct question about the physical
evidence in the context of the particular case. Both the law enforcement and
defense communities should be exploiting this resource to a much greater
extent than has historically taken place. In Chapter 11 we’ll discuss the edu-
cation and communication that must take place for the criminalist to provide
optimal assistance to their clients.
Although not documented in any systematic fashion, conventional wis-
dom says that the first suspect identified by the detectives working a case is
frequently the one convicted, or at least arrested. Perhaps no compelling
evidence may point to another individual, but neither have alternative pos-
sibilities necessarily been fully explored. Especially in the case of highly pub-
licized crimes or protracted investigations, law enforcement is under great
pressure to apprehend and convict someone, anyone, for the crime. In the
effort to assign responsibility and assure society that the bad guys are off the
streets, objectivity may become an inadvertent victim. When individuals with
a stake in the outcome or a hunch as to the culprit (e.g., the detective or
prosecutor) are allowed solely to determine what analysis is done by request-
ing some specific examination, there is potential, not necessarily for a bad
analysis, but for an irrelevant one. With access to vital case information, the
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250
Principles and Practice of Criminalistics
analyst has a chance to retrieve a useful analysis from obscurity. The partic-
ipation of the analyst in determining both the kinds of evidence that will be
examined and the types of examinations to be performed is a vital prereq-
uisite to a competent analysis. In Sidebar 10, we present a case in which the
independent analyst’s understanding of the crime was the key to uncovering
a valuable piece of evidence.
All of the preceding assumes that the forensic analyst in fact possesses
the knowledge, education, and experience required to consider the evidence
intelligently and thoughtfully in light of the case circumstances. In this day
and age of specialization and automation, it is sometimes left to the detective
or attorney to fill the role of coordinator and generalist, simply by default.
We will address the issue of education in forensic science more specifically
in Chapter 12.