Nevada Sexual Assault Case Exposes State’s Failure to Develop Standards for Expert Testimony

Defense attorneys for Noe Perez, a Nevada man convicted of sexual assault last year, are hoping that doubts raised about the qualifications of the prosecution’s expert witness will be enough to get their client a new trial. On a grander scale, defense communities around the state want the Nevada Supreme Court to use Perez’s case as an opportunity to put a stop to the state’s “Wild West attitude” regarding expert testimony in criminal cases and set clear parameters for the courts to use in determining whether a witness is qualified to give expert testimony. “In Nevada, you can be an expert in almost anything…There is no limit to who is an expert.” said Norm Reed, a Nevada public defender. The Nevada Supreme Court has held that “as long as the testimony helps the jury, it should be allowed to be heard.”

Although attorneys are given a wide berth in their presentation of evidence in Georgia and many other states, rumblings have been growing for years about the dangers of unqualified expert testimony. When a seemingly well-informed individual takes the stand and offers an opinion about a matter not in his professional repertoire, jurors can be easily misled. As judges tend to place the responsibility of weighing expert witness credibility on the jury, an unqualified witness can have a dangerous effect on the outcome of the case.

In Perez’s case, the prosecution offered an expert, a clinical forensic psychologist, who described Perez’s behavior leading up to the sexual assault as “grooming” his victim. Although the psychologist had experience in conducting psychosexual evaluations, he had never conducted a study nor published any materials on the issue of “grooming.” He simply testified about the behavior in generalities. Perez’s defense attorneys did not object to the subject matter of the testimony, rather they argued the psychologist’s testimony prejudiced the jury as he was not qualified to provide expert testimony on “grooming” behavior.

One solution proposed by the defense community is for Nevada to join the ranks of the rest of the country and promulgate standards for determining who can be deemed an expert. Under the Supreme Court’s Daubert standard, a judge weighs multiple factors before determining the admissibility of the evidence, including whether the testimony derives from the scientific method or has been subject to peer review. However, the Supreme Court’s broad interpretation of what qualifies as “science” has led to the birth of “junk science” and many wrongful convictions. Such techniques as bite-mark, boot print, and blood spatter analysis rose to great popularity in the 1980s and 1990s, and many police departments and district attorneys relied heavily on such evidence—which was later revealed to have little to no scientific basis or reliability. This unreliable evidence was used to arrest and convict potential suspects. Defense teams continue to work to exonerate many of these individuals as DNA evidence becomes available.

Despite their flaws, battling unqualified “experts” can still be very challenging for the defense. Often, if a prosecutor offers an expert witness who comes to one conclusion, defense attorneys often have great difficulty persuading jurors even if several of their own experts reach the opposite conclusion. In another Nevada case in 1991, jurors chose to believe the one expert called by the State, who found that bite marks on the victim implicated the defendant in a gruesome rape and stabbing case, even though the defense presented nine dentists who disagreed. Eventually, the defendant was exonerated by DNA evidence and released.

While Nevada is one of only a few states that lack formal rules governing the admission of expert testimony, there is still no national standard to determine who can testify as an expert. There is no license, no registration, and no larger body that acts as a gatekeeper against all the “would-be” experts trying to weigh in on cases. States are still left to their own devices to implement guidelines for expert qualification. As seen in Nevada, some states still choose to operate without any restrictions.

It is abundantly clear that courts everywhere should reevaluate the rules governing the admission of expert testimony—particularly in criminal cases. Jurors need to be able to trust the information they receive from someone deemed to be an expert. Otherwise, they are rendering verdicts and sending people to prison based on unreliable science or unqualified expert opinions.