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State v. Macumber, 544 P.2d 1084 (Ariz. 1976)

Case (cite)
State v. Macumber, 544 P.2d 1084 (Ariz. 1976)
Type of proceeding
Type of claim
Type of claim (second claim)
Expert evidence ruling reversing or affirming on appeal:
What was the ruling?
Error to Exclude
Type of evidence at issue:
Firearms identification
Defense or Prosecution Expert
Name of expert(s) who were the subject of the ruling
Charles M. Byers
Summary of reasons for ruling
The court held that the trial court erred in excluding the expert's testimony and in finding him unqualified. The expert had a degree in chemistry, had studied firearms identification and been employed by weapons manufacturers and written four articles.The defense was offering him to counter the prosecution's expert and the jury should have been allowed to hear his testimony given that a critical piece of evidence was the bullets linking the appellant to the gun.
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
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


“A person need not be expert in a detailed aspect of a specialized area of knowledge; it is sufficient if he can be qualified as expert in that specialty. It was therefore sufficient that Byers qualified as an expert in firearms identification without having qualified as a specialist in the comparison of ejector markings. During the course of this case, he was able to form an opinion as to the comparison of ejector markings based on his study of firearms identification in general. His opinion was contrary to the expert testimony of the prosecution. He should have been allowed to testify and to offer his opinion.”