601.1Reliability, Admissibility, and Daubert

Last Updated: 12/01/23

Key Concepts

  • Expert testimony must be relevant and a good “fit” for the case in order to be deemed helpful to the trier of fact.
  • The witness must also be properly qualified as an expert through education, training, experience or otherwise, and any opinion offered must fall within the witness’s area of expertise.
  • North Carolina is now a “Daubert state,” which means expert testimony must satisfy the three-part reliability test found in Rule 702(a) to be admissible.

To be admissible, the testimony offered by an expert witness must be:

A.  Relevant;
B.  From a witness properly qualified as an expert;
C.  Reliable, per the three-prong test of Rule 702(a) and Daubert; and
D.  Not excluded by another rule of evidence, such as Rule 403 (unfairly prejudicial).

Each of these issues is summarized in more detail below. For a more comprehensive discussion of this topic, see also Criminal Evidence: Expert Testimony,” Jessica Smith, NC Superior Court Judges’ Benchbook, August 2017.

Relevance and “Fit”

The first requirement, pursuant to Rule 702(a), is that the expert testimony will “assist the trier of fact to understand the evidence or to determine a fact in issue.” In other words, the testimony must not only be “relevant” in the sense that it relates to an issue in the case, see G.S. 8C-1, Rule 401 (Definition of “relevant evidence”); State v. Lopez, 264 N.C. App. 496 (2019) (no error in excluding defense expert testimony regarding effects of alcohol in causing memory loss, because it was not relevant to issue of whether victim was "physically helpless" as a result of drinking); State v. Oakes, 209 N.C. App. 18 (2011) (no error in excluding testimony of defense expert on intent to kill, where charge was felony-murder so intent was irrelevant), but also that the testimony “must provide insight beyond the conclusions the jurors can readily draw from their ordinary experience,” State v. McGrady, 368 N.C. 880 (2016).

The expert testimony must also “fit” the facts of the case, meaning that the proffered testimony “is sufficiently tied to the facts of the case that it will aid the jury in resolving a factual dispute.” State v. Babich, 252 N.C. App. 165 (2017) (citing Daubert v. Merrell Dow Pharmaceuticals, Inc., 509 U.S. 579 (1993)).

Qualifications of the Witness

The proposed expert witness must also be “qualified as an expert by knowledge, skill, experience, training, or education.” See G.S. 8C-1, Rule 702(a). The key inquiry is whether the witness has some expertise that places him or her in a “better position than the trier of fact to have an opinion on the subject.” State v. McGrady, 368 N.C. 880 (2016). The witness’s expertise will often come through education and advanced study, but this is not mandatory – it may also be obtained through practical experience or on-the-job training and experience. See State v. Morgan, 359 N.C. 131 (2004) (witness qualified to testify about blood spatter based on experience and training); State v. Cooper, 229 N.C. App. 442 (2013) (error to exclude defense computer expert who worked in the field for many years, but had no formal training as a forensic computer analyst); State v. Norman, 213 N.C. App. 114 (2011) (state’s witness qualified to testify based on employment and experience, despite lack of a formal degree or certification in the applicable fields).

Practice Pointer

Stay in your lane 
A common issue which arises under this prong is a dispute about whether an expert is testifying outside his or her area of expertise. “For example, a witness with a Ph.D. in organic chemistry may be able to describe in detail how flour, eggs, and sugar react on a molecular level when heated to 350 degrees, but would likely be less qualified to testify about the proper way to bake a cake than a career baker with no formal education.” State v. McGrady, 368 N.C. 880 (2016). The prosecutor should consult with the expert witness before trial, and make sure they have the same understanding how the witness will be tendered (“as an expert in the field of X”), and whether the witness is appropriately qualified to render the opinion the state wants to elicit on that topic.

Rule 702 Reliability Requirements – the Daubert Standard

In 2011, Rule 702(a) was amended to add a three-part reliability test. In essence, this statutory change overruled the prior admissibility standard used in North Carolina, as stated in Howerton v. Arai Helmet, Ltd., 358 N.C. 440 (2004), and replaced it with a more rigorous reliability analysis that is commonly referred to as the “Daubert standard.” While the amendment “did not change the basic structure of the inquiry” under Rule 702(a), it “did change the level of rigor that our courts must use to scrutinize expert testimony before admitting it.” State v. McGrady, 368 N.C. 880 (2016).
Under the Daubert standard, expert testimony in the form of an opinion may only be offered into evidence if: (i) the testimony is based upon sufficient facts or data; (ii) the testimony is the product of reliable principles and methods; and (iii) the witness has applied the principles and methods reliably to the facts of the case. This revised standard applies to all cases “commenced” (i.e., charged or indicted) after October 1, 2011.

  1. Key Daubert Cases to Know
    1. Daubert v. Merrell Dow Pharmaceuticals, Inc., 509 U.S. 579 (1993): held that the trial judge must act as a “gatekeeper” and make a flexible determination as to whether or not an expert should be allowed to give the proffered opinion, based on factors including but not limited to: (i) has the theory or technique been tested; (ii) has it been subjected to peer review; (iii) what is the potential rate of error; (iv) are there standards for controlling its operation; and (v) is it generally accepted?
    2. General Electric Co. v. Joiner, 522 U.S. 136 (1997): explained that a trial court’s decision to admit (or exclude) expert testimony under a Daubert analysis will be reviewed using an abuse of discretion standard on appeal.
    3. Kumho Tire Co. v. Carmichael, 526 U.S. 137 (1999): clarified that the Daubert standard applies to all proposed expert testimony, and not just “scientific” testimony.
  2. How the Daubert Standard Works in Court
    The party seeking to introduce the proffered testimony must ask sufficient foundation questions to satisfy the trial judge that all three prongs of the standard – (i) based upon sufficient facts; (ii) using reliable methods; and (iii) actually applied to the present case – have been fully satisfied. See, e.g., State v. Hayes, 256 N.C. App. 559 (2017) (prejudicial error to admit expert testimony on retrograde extrapolation when witness’s testimony failed to satisfy third prong – opinion was not sufficiently tied to facts of the particular case).
    In most cases that involve routine and well-established areas of expertise (e.g., fingerprints, DNA, or drug identification), this will likely not require any interruption in the normal presentation of the evidence. The same basic questions that the prosecutor would be likely to ask the witness anyway (educational background, training, methodology, analysis of the facts in the present case, and so on) should easily satisfy the Daubert standard.
    But if the expert testimony involves new technologies, untested methods, or an unusual area of expertise, the opposing party may seek to challenge the admissibility of that testimony on Daubert/702 grounds, which is typically done through a motion in limine, and the court may need to hold a separate voir dire hearing to address the issue.
    Trial judges are not statutorily “required” to make specific findings of fact and conclusions of law on the record as to each of the Daubert factors, but recent cases strongly indicate that the judge “should” do so. See State v. Abrams, 248 N.C. App. 639 (2016) (“in ruling on the expert's admissibility, the trial court should identify the Daubert factors and make findings of fact and conclusions of law, either orally or in writing, as to the expert’s admissibility”).
  3. Impact on Pre-Daubert North Carolina Expert Witness Cases?
    “Our previous cases are still good law if they do not conflict with the Daubert standard.” State v. McGrady, 368 N.C. 880 (2016). In other words, pre-2011 appellate cases which address issues such as admitting or excluding expert testimony based on relevance, “fit” with the facts, witness qualifications, or prejudice should still hold the same precedential value. However, any pre-2011 cases that addressed the admissibility (or exclusion) of expert testimony based on issues such as the reliability of the technique or its degree of acceptance by the scientific community should be carefully examined to ensure that they are not in conflict with the new standard.

Admissible Under Rule 403

Finally, even if the expert testimony is otherwise admissible under Rule 702, the court may still exclude it under Rule 403 if it is unfairly prejudicial, misleading, confusing, etc. See GS. 8C-1, Rule 702(g) (court may “disqualify an expert witness on grounds other than the qualifications set forth in this section”). See, e.g., State v. King, 366 N.C. 68 (2012) (no abuse of discretion in excluding repressed memory testimony under Rule 403, where trial court concluded that probative value of the proposed testimony was outweighed by danger of unfair prejudice because recovered memories were, in trial court's opinion, of uncertain authenticity and susceptible to possible alternative explanations).

Similarly, supporting evidence for the opinion that would otherwise be admissible under Rule 703 (“Bases of opinion testimony by experts”) or Rule 705 (“Disclosure facts or data underlying expert opinion”) may be excluded if it is deemed inadmissible under Rule 403. See State v. Coffey, 336 N.C. 412 (1994) (evidence of defendant’s prior convictions was not admissible under Rule 705, even though the convictions constituted part of the basis of expert’s opinion regarding defendant’s mental state, because the probative value was outweighed by risk of prejudice).

Portions of this entry were excerpted from the North Carolina Superior Court Judges’ Benchbook, “Criminal Evidence: Expert Testimony,” Aug. 2017, Jessica Smith.