BOX 1.2

A Further Note on the Definition of Biometrics

The committee defines biometrics as the automated recognition of individuals based on their behavioral and biological characteristics. This definition is consistent with that adopted by the U.S. government’s Biometric Consortium in 1995. “Recognition” does not connote absolute certainty. The biometric systems that the committee considers always recognize with some level of error.

This report is concerned only with the recognition of human individuals, although the above definition could include automated systems for the recognition of animals. The definition used here avoids the perennial philosophical debate over the differences between “persons” and “bodies.”1 For human biometrics, an individual can only be a “body”. In essence, when applied to humans, biometric systems are automated methods for recognizing bodies using their biological and behavioral characteristics. The word “individual” in the definition also limits biometrics to recognizing single bodies, not group characteristics (either normal or pathological). Biometrics as defined in this report is therefore not the tool of a demographer or a medical diagnostician nor is biometrics as defined here applicable to deception detection or analysis of human intent.

The use of the conjunction “and” in the phrase “biological and behavioral characteristics” acknowledges that biometrics is about recognizing individuals from observations that draw on biology and behaviors. The characteristics observable by a sensing apparatus will depend on current and, to the extent that the body records them, previous activities (for example, scars, illness aftereffects, physical symptoms of drug use, and so on).


1R. Martin and J. Barresi, Personal Identity, Malden, Mass.: Blackwell Publishing (2003); L.R. Baker, Persons and Bodies: A Constitution View, Cambridge, England: Cambridge University Press (2000).

Many traits that lend themselves to automated recognition have been studied, including the face, voice, fingerprint, and iris. A key characteristic of our definition of biometrics is the use of “automatic,” which implies, at least here, that digital computers have been used.2 Computers, in turn, require instructions for executing pattern recognition algorithms on trait samples received from sensors. Because biometric systems use sensed traits to recognize individuals, privacy, legal, and sociological factors are

“biometrics” overlap both in subject matter—human biological characteristics—and in historical lineage. This report’s definition of biometrics is consistent with ISO/IEC JTC 1/SC 37 Standing Document 2, “Harmonized Biometric Vocabulary, version 10,” August 20, 2008.


Early biometric systems using analog computers and contemporary biometric systems using optical comparisons are examples of nondigital processing of biometric characteristics.

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