ABSTRACT
In determining the appropriate weight or strength of forensic evidence, one must be aware of the both the associative and discriminative power of that evidence. Although much of traditional forensic science research has focused on best practices for establishing positive associations, for many forensic tools, the power to discriminate and uniquely identify individual sources is largely unknown and sometimes highly disputed. This chapter defines the ideas of association and discrimination in a forensic science context. It discusses the related notions of sensitivity and specificity of testing procedures and describes potential issues with reliance on databases alone for determining the discriminatory power of evidence. It provides numerous examples of how forensic procedures with unknown or weak discriminatory power have led to inappropriate determinations and concludes by offering thoughts on how these issues can be addressed in ongoing research.
