Legal Aspects of Obtaining Evidence for Analysis by Forensic Techniques

Through the examination of trace evidence, many forensic techniques can establish a link between a suspect and the scene of a crime. Blood, saliva, semen, hairs, fibers, soils, glass, and fingerprints have all been used in this manner. In addition, handwriting and voice exemplars, bite marks, and gunshot residues have also been employed to provide a nexus between a suspect and a crime. All these methods require some form of cooperation on the part of the suspect, ranging from his passive presence for fingerprinting and extraction of blood to his more active participation in providing voice and handwriting exemplars. This contact between the investigator and the suspect has generated constitutional litigation. Defendants have argued that submission to these techniques: (1) violated the privilege against self-incrimination under the Fifth Amendment, (2) violated the right to counsel under the Sixth Amendment, (3) infringed upon the right to be free of unreasonable searches and seizures under the Fourth Amendment, and (4) deprived them of due process of law. This paper will examine the judicial response to these constitutional challenges and the impact these decisions will have on the forensic sciences.