Witnessing Identification

The technique of latent fingerprint identification enjoys a remarkable degree of credibility, even in the adversarial climate of the Anglo-American criminal trial. Latent fingerprint examiners (LFPEs) are treated with a high degree of deference in court proceedings. I trace this to the historical process by which latent fingerprint examiners constructed rules of method and practice which allowed them to present fingerprint identifications as matters of fact. First, LFPEs maintained professional jurisdiction over the interpretation of fingerprint evidence, even while suggesting that the evidence was `speaking for itself'. Second, LFPEs devised rules of method and practice which encouraged unanimity and consistency within the profession. Finally, LFPEs managed cases of error by attributing failure to individual practitioners rather than to the method. I conclude that LFPEs offer a highly idiosyncratic model of scientific evidence, one which new forensic identification techniques, such as DNA typing, will be able to emulate only with difficulty.