sufficient controversy about the methods for assigning statistical weight so that they could not be considered generally accepted. In the sole federal appellate ruling, the Eighth Circuit Court of Appeals reversed a federal trial court's decision to admit DNA typing evidence and directed the lower court to hold a full hearing on admissibility.29 In the spring and summer of 1990, an intermediate-level appellate court in Texas30 and the supreme courts of South Carolina,31 Georgia,32 North Carolina,33 and Massachusetts34 were among the courts that considered the admissibility of DNA evidence. These opinions are of particular interest, because they were issued after sustained debate in the legal and scientific communities about possible flaws in DNA typing technology and possible inadequacies in the population databanks. The courts in Texas, South Carolina, Georgia, and North Carolina upheld the admissibility of DNA evidence; Massachusetts rejected it because of concerns about the adequacy of population genetic interpretation.
In Kelly v. Texas, the defendant appealed from a murder conviction, challenging as error the trial court's admission of evidence that compared a semen sample from the crime scene to a blood sample of the suspect. The defendant did not challenge the principles of DNA typing or the general qualifications of the state's five experts. He did attack the methods of the testing laboratory and the statistical expertise of the witnesses. The appellate court was informed that outside experts had twice verified the laboratory's procedures and results. In upholding the trial court's decision to admit the evidence, the appellate court specifically acknowledged the "validity" of the laboratory's techniques.
In July 1990, the Supreme Court of Georgia decided Caldwell v. State , a death-penalty case. The appeal grew out of a trial court's decision after a Frye hearing (that involved testimony by 10 experts) to admit DNA evidence. Both at the Frye hearing and on the appeal, no challenge was made to the scientific principles or general techniques used by the forensic laboratory. The focus was on how the laboratory declared a match between samples, the validity of its probability calculations, and its procedures to ensure quality control. In deciding the appeal, the court first considered whether it was appropriate for the trial court to use a Frye hearing to determine whether the laboratory had performed its test with reliable techniques and in an acceptable manner. It concluded that, because of the complexity of the issues and a lack of national standards, the inquiry was appropriate. Although noting that errors, including false positives, could occur, the court ruled that the laboratory's protocol was "adequate to meet these concerns."
The court addressed how the laboratory had conducted a band shift analysis and calculated the power of identity. Despite band shifting, the laboratory had originally decided a match by visual examination. During the course of the trial, as a result of criticism of that technique, it reana-