Continuing developments in molecular biology are sure to spawn further changes in DNA testing in the future. New innovations often have a honeymoon period in which they are rapidly embraced by the courts, followed by a period of more critical scrutiny. When RFLP tests were first introduced in 1988, for example, they were virtually unchallenged. By 1991, however, serious questions were being raised about quality control and about the assumptions underlying statistical estimates. Lawyers should bear this history in mind when evaluating new DNA testing methods. It often takes time for problems to be identified and for scientific dissent to emerge.
At the time of this writing, STR testing is widely used. Although there is still some controversy about interpretation in some cases, particularly those involving mixtures and low quantities of DNA, the technology per se appears to be well established. Much of the current controversy, however, still centers around the flexibility associated with laboratory protocols and the possibility of errors and contamination occuring in the laboratory. Emerging issues appear to be questions regarding the appropriate statistics to apply in increasingly common cases where suspects are initially identified by DNA testing results (“cold hits” or “database trawls”) and concerns over the lack of independence of most DNA testing labs from law enforcement agencies. Y- STRs and mtDNA are less widely used and may still be vulnerable to admissibility challenges as well as to attacks on the quality of results in specific cases.
Although this book will be updated on a regular fashion, there is no replacement for scanning through Westlaw, LEXIS and the internet to find the most recent developments in the law. For example, in any three-month period, there may be dramatic changes in the DNA landscape of research that you will need to be aware of if you have a case with these issues.
In the event you work with the government, you can obtain access to the FBI’s most recent data as well as their experts. If you are a defense lawyer, you might want to contact the lawyers involved with the NACDL DNA Task Force who specialize in DNA litigation or utilize web based resources like www. bioforensics.com.
The People v. Michael Antonio Pizarro. Informative court ruling dealing with how DNA mixtures should be interpreted.
Koehler, J. (1996). On conveying the probative value of DNA evidence: Frequencies, likelihood ratios and error rates. University of Colorado Law Review. 67: 859-886.
Koehler, J. (1995). The random match probability of DNA evidence: irrelevant and prejudicial?. Jurimetrics. 35: 201-218.