persons. For some DNA typing methods, the technical basis is well accepted. For others, important scientific questions must be resolved before they are appropriate to use in court.
New developments in DNA technology probably will, and at first should, be the subject of in limine hearings (those conducted by a court in deciding on admissibility), as has been the case in recent instances when present technology has been tested. As a general rule, generation of evidence with such new technology should be encouraged if it is adequately supported in court hearings. It is highly desirable that experts in molecular genetics and statistical analysis review new developments and pass on them at a variety of conferences and through published papers. Until there is some consensus in this field, results of using new techniques may not be admitted; a testing period for the new techniques will be needed to determine whether there are unforeseen errors or difficulties, and it will take time to compile the necessary databanks. Otherwise, the normal rules with respect to new developments can be relied on. In fact, new developments should present less difficulty than has been posed by present DNA typing technology, because much of the theory will have already been tested and accepted by the courts.
The issue for courts will be to discern when a technology is so different as to require a full admissibility hearing. Admissibility hearings might be required to evaluate the underlying principle of a scientific method of identification, the particular method for applying the principle, and the performance of a test in a particular case. Regarding the underlying principles, there is, as we have noted, no longer any question concerning the principle that DNA can be used to obtain identification information; admissibility hearings need no longer address the question. Regarding the particular method for applying the principle, the inquiry will depend on the new method or technology. For example, use of a previously unused DNA probe in the context of the basic RFLP technique might require an admissibility hearing on whether the properties of the particular probe (e.g., pattern, sensitivity, or population genetics) are scientifically accepted. Methods of correcting for shifted DNA patterns (that would otherwise fall outside the usual matching rule) might require an admissibility hearing concerning whether the correction procedure has gained scientific acceptance, inasmuch as this substantially changes the method of declaring a match. The use of PCR amplification for sample preparation might require a pretrial hearing on the properties of the technique, because it introduces a novel issue considered by only a few courts thus far—the synthesis of evidence by amplification. And the use of various detection technologies for PCR products might require a pretrial hearing about the characteristics of the detection method and its sensitivity to artifacts. In each case, the court can properly limit inquiry to the substantially novel aspects of the technology, focusing on whether