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State v. Boss, 577 S.W.3d 509 (Mo. Ct. App. 2019)

Case (cite)
State v. Boss, 577 S.W.3d 509 (Mo. Ct. App. 2019)
Type of proceeding
Type of claim
Type of claim (second claim)
Expert evidence ruling reversing or affirming on appeal:
What was the ruling?
Correct to Admit
Type of evidence at issue:
Firearms identification
Defense or Prosecution Expert
Name of expert(s) who were the subject of the ruling
Jason Crafton
Summary of reasons for ruling
The court reviewed the expert's testimony re the reliability of the AFTE theory of identification and ruled that it was sufficiently reliable under state rule of evidence (modeled after rule 702). The court noted that Defendant could use NAS2008 to challenge the testimony during cross-examination, but the report itself was not enough to be the basis for excluding the evidence.
The jurisdiction’s standard for expert admissibility at the time – list all that apply: (Frye), (Daubert), (Post-2000 Rule 702), (Other)
Second standard
Rule 702
Did lower court hold a hearing
Names of prosecution expert(s) two testified at hearing
Names of defense expert(s) who testified at hearing (or None).
Discussion of 2009 NAS Report (NAS2009)
Discussion of 2016 PCAST report (PCAST)
Discussion of error rates / reliability
Frye Ruling
Limiting testimony ruling
Language imposed by court to limit testimony
Ruling based in prior precedent / judicial notice
Daubert ruling emphasizing – which factors – (list 1-5)
Ruling on qualifications of expert
Ruling on 702(a) – the expert will help / assist the jury
Ruling on 702(b) – the testimony is based on sufficient facts or data
Ruling on 702(c) – the testimony is the product of reliable principles and methods
Ruling on 702(d) – reliable application of principles and methods to the facts of the case


1. The review standard re admissibility of evidence in Missouri: “[W]e will not disturb this [broad] discretion unless it is against the logic of the circumstances and so unreasonable as to show a lack of careful consideration.” 2. In determinating the realiability of expert testimonies, Missouri adopted the same flexible Daubert standard, “[n]o single factor is necessarily disposiive of the reliability of a particular expert’s testimony.” 3. The court acknowledged NAS2008’s potential challange to firearms identification’s scientific validity, but ruled that not enough to render the testimony inadmissble. “[Defendant] was free to challenge [the expert’s] conclusions and point out the weakness of analysis to the jury during cross-examination on the basis of this report . . . However, weight and credibility are the province of the jury . . . 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 admissble evidence.” (internal quotation ommitted)