in the 1930s—the firearms examiner faces the formidable cognitive task of forming a mental pattern of identifying marks and features on bullet and cartridge case evidence. That pattern must then be matched to those from other exhibits.1

Individualization and Identification: Class, Subclass, and Individual Characteristics

The label “firearms identification” is another instance in which language can be a bit elusive. Although “the terms ‘identification’ and ‘identity’ are used constantly by practitioners” of criminalistics, or the forensic analysis of evidence, Kirk (1963:236) argued that the usage is an “unfortunate failure of nomenclature.” Rather than identification (as that term is commonly understood), Kirk argues that “criminalistics is the science of individualization:”

The criminalist does not attempt identification except as a prelude to his real function—that of individualizing. The real aim of all forensic science is to establish individuality, or to approach it as closely as the present state of the science allows…. What was actually done was not the identification of the fingerprint, but rather the individualization of a person as the one who left the fingerprint…. [Likewise,] if the firearms examiner said that the bullet was a Colt 45 A.C.P. but could not individualize the gun that fired it, his value would be relatively slight.

Thornton and Peterson (2002:8, 9) further differentiate between the two terms: “Individualization is the process of placing an object in a unit category which consists of a single unit. Individualization implies uniqueness; identification, strictly speaking, does not require it.” They also note the frequent use in forensic science of “identification” when “individualization” is meant, but recognized that “it is a constraint imposed by our language”; relying on the term “individualize” would likely lead to public confusion. “It should be appreciated, however, that the process of identification means one thing to the forensic scientist, and another thing to the botanist or the zoologist.” (See also Champod [2000:1077] on “individualization” versus “identification.”)

The phrasing of “individualization” as the act of associating an object


Further information on current practice in firearms identification and images connected with that work are available through resources at the Association of Firearm and Tool Mark Examiners ( and the Scientific Working Group for Firearms and Toolmarks ( Additional information and images—and tools for simulating the use of the comparison microscope for comparing bullet and cartridge evidence—are accessible at

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