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D.
Standardization
Unlike other industrial and clinical manifestations of applied science, forensic
science has traditionally shied away from any kind of oversight, including
standardization. This has begun to change radically over the last decade, in
large part because of the attention focused on the field by the advent of DNA
* Particularly for biological analyses, two types of “control” samples have evolved that
don’t control for anything, but do serve other important functions. The so-called 
 
substrate
control
— a sample taken from an apparently unstained area adjacent to a suspected
physiological fluid stain — is more appropriately called a 
 
substrate sample
. It provides
important information about what might be lurking in the background that might confuse
results from the observed stain; because the answer is previously unknown, it does not
meet the criterion of a control. The second example concerns the threshold “controls”
used in the reverse dot-blot detection of PCR products in DNA typing. These “C” and “S”
dots simply give information about the amount of amplified sample introduced into the
test system (and for the “S” dot even further caveats exist). As such, they do not meet the
criterion for a control that indicates that the test system (in this case, amplification and
hybridization) is functioning properly. This role is fulfilled by a known DNA sample that
is run as a positive amplification control.
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Good Laboratory Practice — Establishing Validity and Reliability
231
testing. Efforts at standardization ideally emerge from the initial cross-labo-
ratory validation effort. Sometimes it is necessary to backtrack if laboratories
have developed similar protocols independently. Methods may be standard-
ized against a protocol or a sample. In other words, laboratories can agree
to use exactly the same protocol to ensure that comparable results are
obtained. Or control samples can establish that two slightly different proto-
cols still produce the same results. In forensic science, it is often more prac-
tical to employ the latter method as it allows for greater flexibility while still
demonstrating reliability.
Several organizations have developed complementary programs that
address these different approaches. The American Society for Testing and
Materials (ASTM) is a well-established organization that provides a frame-
work for any discipline wishing to develop a nucleus of standards. The ASTM
blueprint, developed initially for use in industry, focuses on methods and
protocols. For industrial and clinical applications, a goal is to institute abso-
lutely standardized protocols throughout the industry. The ASTM Committee
E-30 on Forensic Sciences was created in 1970 to address the process of
standardizing the methods and terminology that are particular to the field.
ASTM E-30 is split into a number of subcommittees, one of which is crimi-
nalistics. Although some material has been developed (ASTM, 2000) and those
standards have been incorporated by some laboratories as part of their in-
house protocols, no forensic discipline has formally adopted ASTM standards.
The complement to standardizing against protocols is standardizing
against known samples. The National Institute of Standards and Technology
(NIST) develops and distributes standard materials for a myriad of testing
procedures. NIST materials are used regularly in various forensic disciplines
to establish that a particular instrument or method is giving the expected
results. Other accessory devices, such as NIST-traceable thermometers, also
assist the forensic laboratory in standardizing its methods.
In 1989, in response to the increased scrutiny that came with DNA
testing, the FBI sponsored a pioneer working group, then called Technical
Working Group in DNA Analysis Methods (TWGDAM). This group, com-
prising representatives from public laboratories throughout the country,
compiled a document outlining guidelines for qualifications, training, vali-
dation, testing, and report writing. Shortly thereafter additional “TWGs”
were formed in an effort to address similar issues in the other forensic
disciplines. The adjective “scientific” has now replaced the word “technical,”
and all the acronyms begin with “SWG” in stead of “TWG.” Most are works
in progress, although just this year SWGMAT released several documents
addressing trace analysis, fibers, hair, and paint. The SWG guidelines do not
attempt to provide specific methods or protocols. Rather they direct that
validated protocols be implemented, and that standard materials be used to
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Principles and Practice of Criminalistics
verify the proper working of any methods employed. For whatever reason,
the community has directed its resources toward the SWGs rather than the
ASTM groups. It is possible that at some future point, those efforts may be
merged.