(1999), however, the Supreme Court reversed the
Appellate Division’s application of Spann in a case
involving expert testimony on the similarity in
composition of lead bullets taken from the body of a
murder victim and from the defendant, comparing it to
expert testimony on matching fibers. See also State v.
Koedatich, 112 N.J. 225 (1988).
If expert evidence, because of its lack of scientific
reliability, poses such a danger of prejudice, confusion,
and diversion of attention that it exceeds its ability to aid
the fact finder, it must be excluded. Examples include
“linkage analysis,” based on the “signature” aspects of two
crimes, State v. Fortin, 162 N.J. 517 (2000), and expert
testimony that the defendant did not fit the
psychological profile of a rapist. State v. Cavallo, 88 N.J.
508, 520 (1982).
Expert testimony regarding Child Sexual Assault
Accommodation Syndrome is inadmissible to establish
guilt or innocence, and is admissible only to establish
that the victim’s symptoms were consistent with sexual
abuse and to explain delay in reporting abuse or
recantation of allegations of abuse. State v. J.Q., 130 N.J.
554 (1993); see also State v. W.L., 278 N.J. Super. 295
(App. Div. 1995) (testimony on CSAAS beyond limited
evidence permitted by J.Q.).
Expert testimony regarding such matters as post-
traumatic stress disorder is sufficiently reliable. State v.
Hines, 303 N.J. Super. 311 (App. Div. 1997).
Expert testimony is not required in a criminal case
involving cross-racial identification, since the matter is
within the ken of the average juror rather than on
scientific, technical or other specialized knowledge. State
v. Cromedy, 158 N.J. 112, 130 (1999). An instruction
on the issue may be given upon request, but only if
identification is a critical issue in the case and a witness’
cross-racial identification is not corroborated by other
evidence giving it independent reliability. Id. at 132.
A proponent of expert testimony can prove its general
acceptance in three ways: (1) by expert testimony as to
the general acceptance, among those in the profession, of
the premises on which the proffered expert witness based
his or her analysis; (2) by authoritative scientific and legal
writings indicating that the scientific community accepts
the premises underlying the proffered testimony; and (3)
by judicial opinions that indicate the expert’s premises
have gained general acceptance. State v. Harvey, 151 N.J.
117, 170 (1997), cert. denied, 528 U.S. 1085, 120 S.Ct.
811 (2000); State v. Kelly, 97 N.J. at 210; State v. Cavallo,
88 N.J. at 521. The burden is on the proponent of expert
testimony to “clearly establish” its general acceptances.
State v. Harvey, supra; State v. Williams, 252 N.J. Super.
369, 376 (App. Div. 1991). Harvey upheld the
admission of Polymerase Chain Reaction (PCR) DNA
testing as generally accepted in the scientific community.
See also State v. Dishon, 297 N.J. Super. 254, 277 (App.
Div.), certif. denied, 149 N.J. 144 (1997). In State v.
Marcus, 294 N.J. Super. 267, 285 (App. Div. 1996),
certif. denied, 157 N.J. 543 (1998), the Appellate
Division concluded that DNA tests using the restriction
fragment length polymorphism (RFLP) method was
generally accepted and properly admitted.In State v. Freeman, 223 N.J. Super. 92 (App. Div.
1988), a forensic toxicologist testified for the State that
the likely way a victim murdered by cyanide poisoning
had taken the chemical was orally in some water or other
liquid, probably soda, milk, or tea with sugar or lemon.
The expert further testified that it was not likely that food
would be used because the cyanide would burn. The
defendant on appeal argued that the doctor’s testimony
failed to account for the quantity of tea, milk, soda, or
water needed to dilute or cover the taste and burning
effect of cyanide, and thus constituted a “net opinion.”
The court held that “such testimony is not inadmissible
merely because it fails to account for some particular
condition or fact which the adversary considers relevant.”
If the quantity of liquid was relevant, it would have been
an appropriate matter for cross-examination.In State v. Zola, supra, a capital case, the defendant
raised a number of objections to the testimony of the
State’s expert in serology, the identification of bodily
fluids. The expert testified that an elevated level of the
digestive enzyme amylase found in a vaginal sample from
the victim indicated the presence of saliva. The expert
had based this opinion in part upon a review of 1,644
samples of bodily fluids he had previously examined for
amylase activity. The Supreme Court held that while this
data preferably should have been disclosed in discovery,
the reference to them at trial did not have the capacity to
prejudice the defendant, since the defendant was given
the opportunity (albeit belated) to examine the data and
question the expert, and because the defendant’s expert
agreed that the significant amylase level in the sample was
consistent with the presence of saliva, but challenged the
State’s expert’s testimony on a different basis, that the
vaginal sample had not been tested for other
characteristic components of saliva. The amylase testing
was reliable to scientifically indicate the presence of saliva
in the sample, the expert’s suggestion that the defendant
had introduced his or the victim’s saliva into the vagina