Skip to content

People v. Blacknell, 2015 WL 6157479 (Ct. App. Cal. 2015)

Case (cite)
People v. Blacknell, 2015 WL 6157479 (Ct. App. Cal. 2015)
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
Summary of reasons for ruling
Defendant argues that firearms identification should be considered a new scientific technique and re-examined in light of recent criticisms. The court agrees with the Diaz court in finding firearms identification testimony reliable despite the NAS reports, stating that the NAS report does not call for an abandonment of the field. Further, the court relies on precedent to hold that firearms identification has been long accepted in California courts and therefore a Kelly/Frye hearing is not applicable. Finally under Sargon, which requires a reasonable basis for expert testimony, firearms testimony has a reasonable basis and is admissible.
The jurisdiction’s standard for expert admissibility at the time – list all that apply: (Frye), (Daubert), (Post-2000 Rule 702), (Other)
Second standard
Did lower court hold a hearing
Names of prosecution expert(s) two testified at hearing
Murdock, James Hamby
Names of defense expert(s) who testified at hearing (or None).
David Faigman, William Tobin, Clifford Spiegelman (statistician)
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


Trial court reasoning for allowing the testimony: ” It found toolmark testimony had been admitted in California courts for many years and had not been subject to question. Further, reviewing the evidence presented at the hearing, the trial court found toolmark testimony was valid. It considered the “credibility” and “demeanor” of defendant’s experts and found their testimony did not disclose errors in identification procedures. It recognized these experts’ critique was the lack of a statistical foundation for making statements that casings and guns matched to a certain degree of probability. But it was concerned these experts had no experience actually performing toolmark identification. It further found Murdock and the prosecution witnesses credible on the manner in which toolmark analyses are done. Finally, it found the NAS reports, though raising criticisms of the toolmark field, explicitly disclaimed an intent to address the credibility of the field in court. When asked for clarification, the trial court explained it would not be limiting the nature of the statement of probability that an expert could make about a match, leaving it for cross examination to explore the strength of any statement of a probable match.”




Expert testimony in trial court: “He was questioned about the meaning of “practical” certainty or identity. He was questioned about the NAS reports and other criticisms of the field. He was questioned about when examiners reach opposite conclusions and about a lab in Detroit with high error rates. He conceded identifications to the practical exclusion of other guns were not based on statistical models or mathematics.”