Expert Testimony in North Carolina Criminal Trials in a Post-howerton World

• Publication year: 2004
• Citation: Vol. 6 No. 2004

Dean P. Loven⁰

I. Setting the Standard for Expert Testimony under Howerton

For the past several years, controversy existed in North Carolina as to the standard for determining the admission of expert testimony.¹ The North Carolina Supreme Court recently put this controversy to rest in Howerton v. Arai Helmet, Ltd.² In Howerton, the court flatly rejected the gatekeeping test adopted by the United States Supreme Court in Daubert v. Merrell Dow Pharmaceuticals, Inc.³ Instead, the court reiterated its previous three part test: "(1) Is the expert's proffered method of proof sufficiently reliable as an area for expert testimony? (2) Is the witness testifying at trial qualified as an expert in that area of testimony? (3) Is the expert's testimony relevant?"⁴

With respect to the first factor, admissibility is favored when precedent has accepted its admission, and disfavored when such methods have previously been found to be inherently unreliable.⁵ "Where, however, the trial court is without precedential guidance or faced with novel scientific theories, unestablished techniques, or compelling new perspectives on otherwise settled theories or techniques," the trial court must look to other "'indices of reliability' to determine whether the expert's proffered scientific or technical method of proof is sufficiently reliable[.]'"⁶ Such indices include "the expert's use of established techniques, the expert's professional background in the field, the use of visual aids before the jury so that the jury is not asked to 'sacrifice its independence by accepting [the] scientific hypotheses on faith,' and independent research conducted by the expert."⁷ This list, however, is not exhaustive. Thus, while the trial court must make a preliminary foundational inquiry into the basic methodological adequacy of an area of expert testimony,

[t]his assessment does not, however, go so far as to require the expert's testimony be proven conclusively reliable or indisputably valid before it can be admitted into evidence. In this regard, we emphasize the fundamental distinction between the admissibility of evidence and its weight, the latter of which is a matter traditionally reserved for the jury. ⁸

"Therefore, once the trial court makes a preliminary determination that the scientific or technical area underlying a qualified expert's opinion is sufficiently reliable (and, of course, relevant), any lingering questions or controversy concerning the quality of the expert's conclusions go to the weight of the testimony rather than its admissibility."⁹ The court noted that "vigorous cross-examination, presentation of contrary evidence, and careful instruction on the burden of proof are the traditional and appropriate means of attacking shaky but admissible evidence."¹⁰ Finally, the court noted that expert testimony, like any testimony, must be excluded under N.C. Gen. Stat. § 8C-1, Rule 403 "if its probative value is substantially outweighed by the danger of unfair prejudice, confusion of the issues, or misleading the jury, or by considerations of undue delay, waste of time, or needless presentation of cumulative evidence."¹¹

II. Subsequent Application of Howerton

Despite its recent pronouncement, Howerton has already generated appellate decisions concerning the admission of expert testimony. In State v. Taylor,¹² the North Carolina Court of Appeals applied Howerton to expert testimony concerning estimation of defendant's blood alcohol level using retrograde extrapolation analysis. The majority of the court found expert testimony based on this method had previously been accepted, but noted the defendant had specifically challenged the use of the average elimination rate as opposed to the defendant's actual elimination rate in the calculation.¹³ The majority then considered whether use of the average elimination rate was sufficiently reliable. The court reasoned that because the defendant did not challenge the testifying expert's qualifications or the general relevance of the testimony, the defendant had conceded the result was sufficiently reliable to be considered by the jury under the first step in State v. Goode.¹⁴ In reaching this conclusion, the court took pains to note the expert testified that the elimination rate used in the calculations was an average elimination rate and not the defendant's actual elimination rate, and that individuals with prior experience with alcohol would have a higher elimination rate.¹⁵

Judge Tyson concurred in the result, but argued the prior discussion of the use of the average elimination rate was mere dicta because a proper objection was not made at trial, and that admission of such evidence in Taylor was erroneous.¹⁶ Judge Tyson reasoned that the North Carolina Supreme Court had previously rejected the use of statistical averages to predict how a specific action occurred or how an individual may have reacted or responded in a specific case where there are a large number of variables that could affect the measurement.¹⁷ Because the expert improperly relied upon the average elimination rate to form his opinion as to the defendant's blood alcohol level at the time of the accident, the evidence was "hearsay, purely circumstantial, and irrelevant to [the] defendant's alcohol elimination rate and blood alcohol concentration at the time of the accident."¹⁸ He went on to state that admission of such hearsay testimony denied the defendant the right to confront and cross-examine the source of the hearsay declarations.¹⁹ Despite his conclusion that the average elimination rate was improperly admitted, Judge Tyson found the error to be harmless in light of other evidence of defendant's guilt, and therefore voted to affirm the defendant's conviction.²⁰

In State v. Morgan,²¹ the North Carolina Supreme Court addressed the limited issue of the qualifications of an expert in blood stain pattern interpretation. The court concluded that the testifying agent's failure to write or lecture on the topic or take any college level courses on the topic did not disqualify him as an expert, given his completion of two training sessions on bloodstain pattern interpretation, analysis of blood stain patterns in dozens of cases, previous acceptance as an expert in the area, and testimony at trial, including the use of visual aids and distinguishing the differences between blood spatter and transfer stains.²²

The first post-Howerton case to address the admissibility of a new scientific method involved the identification of glass fragments.²³ First, the court noted that the trial court heard extensive voir dire testimony as to the methods the proffered witness used to support the finding that the physical properties of the standard and unknown sample from the defendant's shoe were similar, and supporting the conclusion that the witness "[could] not rule out that the particle did not come from that source [the broken window]."²⁴ Second, the trial court properly determined that the investigator qualified as an expert.²⁵ Finally, the court noted that the relevance of the expert testimony was not questioned.²⁶

In sum, post-Howerton cases, especially Taylor, have put great weight on the jury sorting through the nuances of expert testimony in novel areas even when there is no battle of the experts to sharpen the issues.

III. The Impact of Differences in Criminal and Civil Procedure on the Application of Howerton

With the notable exception for the testimony of mental health experts, the State or North Carolina is generally the proponent of expert testimony in criminal proceedings. As a result, the criminal defendant is generally in the same position as the civil defendant in attempting to suppress the introduction of expert testimony at trial or countering such testimony if it is admitted. However, the tools available to the criminal defendant are different than those available in civil cases, resulting in a different means for attacking such testimony. In addition, the incentive for attacking expert testimony is often different in criminal and civil proceedings. In civil proceedings, expert testimony may be essential to prove an element of the case. Therefore any motion to suppress such testimony may be dispositive. This was the case in Howerton, where the action was a product liability claim alleging the plaintiff's injuries arose from negligent design, manufacture and promotion of the defendant's motorcycle helmet.²⁷ The expert testimony at issue attempted to establish a causal link between the alleged negligent conduct and plaintiff's injury.²⁸ The trial court's decision to exclude the testimony of the three experts resulted in dismissal of the action upon defendant's motion for summary judgment.²⁹

In contrast, expert testimony in criminal cases often is but one piece of evidence considered by the jury in evaluating the guilt or innocence of the defendant.³⁰ Suppression of expert testimony therefore rarely scuttles a criminal prosecution. As a result, the criminal defendant generally has little incentive to seek to suppress expert testimony by way of pretrial motions, relying instead on in limine or voir dire motions to suppress such testimony. Even if a motion to suppress is filed pretrial, the trial court may in its discretion elect to hear the motion during trial.³¹ The trial court will undoubtedly do this in situations where the relevancy of the evidence may be unclear until further evidence is presented at trial. In addition, as a practical matter such motions may be delayed until trial because the expert witness may have to be subpoenaed to travel from another place to testify, and it is more convenient and less costly to make one trip instead of two.

Even if the criminal defendant is in the position to challenge expert testimony at trial, he or she may elect not to do so for strategic reasons. For example, a defendant may choose not to challenge expert testimony on DNA profiling in a rape case where the defendant has...