THE ROLE OF EXPERT WITNESSES IN CRIMINAL CASES IS DISCUSSED ALONG WITH THE SIGNIFICANCE AND USE OF SCIENTIFIC EVIDENCE. REPRINTS OF ARTICLES FROM THE FBI LAW ENFORCEMENT BULLETIN ARE PRESENTED WITH SUGGESTIONS FOR THEIR USE BY LAWYERS IN ESTABLISHING EVIDENCE FOR THE DEFENSE. THESE ARTICLES ARE DIVIDED INTO FIVE MAJOR CATEGORIES -- MEDICINE, FINGERPRINTS, GENERAL CRIMINALISTICS, WITNESSES, PHOTOGRAPHY, AND HANDWRITING. ANOTHER AREA WHICH IS DISCUSSED IS THAT OF VOICEPRINT IDENTIFICATION AND ITS APPLICATION TO FORENSICS. LAWYERS ARE INTRODUCED TO THE NEW FIELD OF NEUTRON ACTIVATION ANALYSIS, WHICH INVOLVES THE CAPABILITIES AND VULNERABILITIES OF TRACE EVIDENCE. THE FINAL GROUP OF DISCUSSIONS INCLUDES TECHNICAL DEFENSES IN DRUG CASES, WHICH DEAL PRIMARILY WITH CHEMICAL IDENTIFICATION OF DRUG SUBSTANCES. THE MATERIALS ARE PRESENTED AS BASES FOR DEFENSE IN CRIMINAL CASES. PROCEDURES ARE OUTLINED FOR THE LAWYER, AND RECOMMENDATIONS ARE MADE FOR CONDUCTING THE CROSS-EXAMINATION OF WITNESSES. EMPHASIS IS ALSO PLACED ON THE USE OF EXPERT WITNESSES IN THESE CASES. TABULAR DATA, PICTURES, AND REFERENCES ARE PROVIDED. (BAC)