In 1993, when the Supreme Court demanded real scientific standards for expert evidence in federal courts, some critics correctly anticipated that several criminal identification techniques would be attacked in the courts with some success: microscopic hair comparison, bite mark analysis, handwriting comparison. Few, if any, predicted what is happening now: The bedrock forensic identifier of the 20th century, fingerprinting, has started to wobble. In a pretrial hearing in a Philadelphia federal court in January, Judge Louis H. Pollak sharply limited the use of fingerprint evidence in a drug-related murder case. He found that there is no persuasive proof that the...