an evidence sample are known to come from the same subgroup. We also discuss the uncertainties of the various calculations.
We discuss but do not propose rules for addressing laboratory error. Laboratory procedures have become more standardized since the last report, largely because of the work of the Technical Working Group on DNA Analysis and Methods (TWGDAM 1991-1995). In addition, DNA-typing and proficiency tests are now common. TWGDAM and the FBI's new DNA Advisory Board can modify their recommendations as technical changes and experience warrant. Rather than make specific technical recommendations, and especially rather than try to anticipate changes, we prefer to leave the detailed recommendations to those groups and trust professional scrutiny and the legal system to call attention to shortcomings. Laboratories now use a variety of testing procedures; in particular, DNA-amplification methods are common and new markers are coming into use. We affirm the importance of laboratories' adhering to high standards, of following the guidelines, and of participating in quality-assurance and accreditation programs.
We make no attempt to prescribe social or legal policy. Such prescriptions inevitably involve considerations beyond scientific soundness. Nevertheless, we recognize the connection between our scientific assessments and the efforts of the legal system to develop rules for using forensic DNA analyses; we describe the relationship between our conclusions about scientific issues and the admissibility and weight of DNA evidence in Chapter 6.
Finally, we recognize that technical advances in this field are very rapid. We can expect in the near future methods that are more reliable, less expensive, and less time-consuming than those in use today. We also expect more rapid and more efficient development of population databases that makes use of DNA already in storage. We urge as rapid development of new systems as is consistent with their validation before they are put into general use.