Scientific Evidence in Criminal Cases

In many criminal cases, parties may wish to introduce various scientific evidence to prove or disprove elements of the charge.  In order to keep uniformity in the process, the Kelly-Frye test was adopted by California courts, including Long Beach,  to ensure that novel scientific methods of proof be based on subject matter that may reasonably be relied on.  This legal test was implemented to comport with the California Evidence Code that requires expert’s testimony must be based on reasonably reliable matter and an expert must be qualified on the subject to which testimony relates. The law is rooted on the holdings of Frye v U.S., and People v Kelly. In Daubert, the United States Supreme Court overruled Frye which held that scientific evidence is admissible only if it is generally accepted in the scientific community, and rules that it is up to the individual judge in a case to decide whether scientific evidence is based on scientific knowledge. This case is based on the Federal Rules of Evidence, which are not consistent with the California Evidence Code

More recently, the California Supreme Court held that the more flexible approach to the admission of scientific evidence outlined in Daubert does not require overruling Kelly.  Therefore, what used to be called the Kelly-Frye rule (or, since Daubert overruled Frye, the Kelly rule) is still good law and courts must still require a preliminary showing of acceptance in the scientific community before novel scientific evidence may be introduced.  The tests that must be met before admission of expert evidence relating to a new scientific technique are:

(1) There must be general acceptance in the scientific community, which may be established by endorsement of the technique in a published California appellate opinion. If it has not been established by this method, courts should use an overview of the literature along with testimony of experts and relevant decisions from other jurisdictions to determine if there is acceptance.

(2) The expert must be qualified; in this regard, an expert may have some interest in the technique (a certain degree of interest must be tolerated if scientists familiar with the technique are to testify at all).

(3) Correct scientific procedures must have been used.

The scientific expert who testifies about this third part of the test is not required to testify regarding the validity of the technique or its scientific acceptance, although he or she must thoroughly understand the technique and be able to testify as to whether the procedures used were correct. According to one DUI Attorney in Long Beach,  One specific area of criminal law where the validity of a particular scientific test was successfully challenged is the HGN test utilized in DUI cases, the court ruled the reliability of the method was questionable and disallowed the results as it pertained to a suspect’s blood alcohol level.

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