The courts are often asked to consider evidence based on cutting edge science and technology, but how is a court to know whether the evidence is sufficiently reliable to make it admissible? That’s where the 3-pronged Kelly rule comes into play. When a novel scientific technique is potentially being used as evidence in your case, gear up for a Kelly hearing.
Before evidence of a new or novel scientific technique, procedure, or device can be admitted in evidence in California courts, the proffering party must meet the requirements of a three-pronged Kelly rule, formerly known as the “Kelly/Frye” rule.
Here’s the three-pronged test (People v Kelly (1976) 17 C3d 24, 30, 130 CR 144):
- The “reliability” of the new scientific technique must be established by showing that the technique has “gained general acceptance in the particular field to which it belongs”;
- Any witness testifying on the general acceptance of the technique must be properly qualified as an expert to give an opinion on the subject; and
- The evidence’s proponent must show that correct scientific procedures were used in the particular case.
The “common-sense purpose” of the Kelly rule requires that it be applied whenever a party is trying to introduce scientific techniques that, though “new, novel, or experimental, convey a misleading aura of certainty.” People v Stoll (1989) 49 C3d 1136, 1156. The express purpose of the rule is to limit the introduction of scientific evidence until it’s “reasonably certain that the pertinent scientific community no longer views [the technique] as experimental or of dubious validity.”
In a Kelly hearing, the novel scientific evidence’s proponent bears the burden of proof; the proponent must present opinion evidence from a qualified expert showing that the evidence is generally accepted in the relevant scientific community and that proper procedures were used. The proponent must also lay a proper foundation showing the accuracy of any scientific or mechanical instrument used in the test, and that the instrument was properly operated or the procedure was properly conducted.
Of course, the opposing side will try to poke holes into each of the proponent’s assertions.
With the speed of changing technology, novel scientific issues are more often an integral part of lawsuits. This means that Kelly hearings will be increasingly common.
Several types of scientific evidence issues are covered in CEB’s Scientific Evidence and Expert Testimony in California. For a list of scientific techniques that have passed the Kelly rule test and those that did not, check out CEB’s California Trial Objections §20.13. On using expert witnesses to meet the Kelly rule test, turn to CEB’s California Expert Witness Guide, chap 4.
Other CEB blog posts you may find useful:
- 10 Tips for Attacking DNA Evidence
- Surprise! Daubert Applies to California Expert Testimony!
- Did Unreliable DNA Evidence Convict an American Student of Murder in Italy?
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