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United States v. Diaz, 2007 WL 485967 (N.D.Cal. 2007)

Case (cite)
United States v. Diaz, 2007 WL 485967 (N.D.Cal. 2007)
Type of proceeding
Type of claim
Type of claim (second claim)
Expert evidence ruling reversing or affirming on appeal:
What was the ruling?
Other; Trial court
Type of evidence at issue:
Firearms identification
Defense or Prosecution Expert
Name of expert(s) who were the subject of the ruling
G. Andrew Smith, Ronald Nichols
Summary of reasons for ruling
The court held that the AFTE theory satsified the Daubert factors, and held that the defendants objections to the CMS method being superior to AFTE did not make AFTE less reliable or qualify as a reason to exclude the AFTE 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
G. Andrew Smith, Ronald Nichols
Names of defense expert(s) who testified at hearing (or None).
Adina Schwartz (John Jay)
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)
All factors
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


“Defendants contend that traditional pattern matching is unreliable in light of the more recent development of CMS. According to defendants, because CMS is based on objective criteria and statistics, it is more reliable under Daubert. That, however, is not the question. The government is only required to use a method that passes under Daubert. It is not required to use the method that best passes Daubert.”




Finally, it is important to note that-at least according to this record-there has never been a single documented decision in the United States where an incorrect firearms identification was used to convict a defendant. This is not to say that examiners do not make mistakes. The record demonstrates that examiners make mistakes even on proficiency tests. But, in view of the thousands of criminal defendants who have had an incentive to challenge firearms examiners’ conclusions, it is significant that defendants cite no false-positive identification used against a criminal defendant in any American jurisdiction.