State v. Raynor, 2020 WL 8255199 (Conn. 2020)

“The Appellate Court has held that a trial court did not abuse its discretion where it concluded that ballistics and firearms analysis fell into that category of scientific principles so firmly established as to negate the need for a Porter hearing. . . . Science, however, is not static. Methodologies are continually challenged and improved so that an approach once favored by the scientific community may later cede to a novel approach or simply fall out of favor in its entirety. . . . The gatekeeping function of the trial court requires, at a minimum, that judges consider any new evidence that a defendant presents when deciding whether to grant or deny a motion for a Porter hearing. To hold otherwise would transform the trial court’s gatekeeping function—which requires judges to regulate carefully which categories of scientific evidence are sufficiently reliable to present to the fact finders—into one of routine mandatory admission of such evidence, regardless of advances in a particular field and its continued reliability.”

Good summary of the variety of limiting language used: “Options include requiring an expert to state that his degree of certainty is only ‘‘more likely than not’’; (internal quotation marks omitted) United States v. Glynn, supra, 578 F. Supp. 2d 574–75; that the identification is to ‘‘a reasonable degree of certainty’’; United States v. Monteiro, 407 F. Supp. 2d 351, 355 (D. Mass. 2006); that the identification is to ‘‘a practical certainty’’; (internal quotation marks omitted) United States v. McCluskey, Docket No. 10-2734 (JCH), 2013 WL 12335325, *10 (D.N.M. February 7, 2013); that the identifying characteristics on two items are ‘‘consistent with’’ each other (internal quotation marks omitted); United States v. Johnson, Docket No. 16 Cr. 281 (PGG), 2019 WL 1130258, *20 (S.D.N.Y. March 11, 2019); that the recovered firearm ‘‘cannot be excluded as the source’’ of the recovered casing; United States v. Shipp, 422 F. Supp. 3d 762, 783 (E.D.N.Y. 2019); or that the expert be requested to describe only similar and distinguishing features without characterizing a conclusion. United States v. Green, 405 F. Supp. 2d 104, 108–109 (D. Mass. 2005).”

Porter standard from FN2: “A Porter analysis involves a two part inquiry that assesses the reliability and relevance of the witness’ methods. … First, the party offering the expert testimony must show that the expert’s methods for reaching his conclusion are reliable. A nonexhaustive list of factors for the court to consider include: general acceptance in the relevant scientific community; whether the methodology underlying the scientific evidence has been tested and subjected to peer review; the known or potential rate of error; the prestige and background of the expert witness supporting the evidence; the extent to which the technique at issue relies [on] subjective judgments made by the expert rather than on objectively verifiable criteria; whether the expert can present and explain the data and methodology underlying the testimony in a manner that assists the jury in drawing conclusions therefrom; and whether the technique or methodology was developed solely for purposes of litigation. … Second, the proposed scientific testimony must be demonstrably relevant to the facts of the particular case in which it is offered, and not simply be valid in the abstract. … Put another way, the proponent of scientific evidence must establish that the specific scientific testimony at issue is, in fact, derived from and based [on] … [scientifically reliable] methodology. …
“Additionally, we recognized in Porter that … [t]he actual operation of each [Porter] factor, as is the determination of which factors should be considered at all, depends greatly on the specific context of each case in which each particular [threshold admissibility] analysis is conducted. … There is, however, a critical postulate that underlies the Porter factors and indeed underlies the entire Porter analysis: in order for the trial court, in the performance of its role as the gatekeeper for scientific evidence, properly to assess the threshold admissibility of scientific evidence, the proponent of the evidence must provide a sufficient articulation of the methodology underlying the scientific evidence. Without such an articulation, the trial court is entirely ill-equipped to determine if the scientific evidence is reliable upon consideration of the various Porter factors. Furthermore, without a clear understanding as to the methodology and its workings, the trial court also cannot properly undertake its analysis under the fit requirement of Porter, ensuring that the proffered scientific evidence, in fact, is based upon the reliable methodology articulated.” (Internal quotation marks omitted.) State v. Edwards, 325 Conn. 97, 124–25, 156 A.3d 506 (2017).”