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People v. Marchan, 2019 WL 4915457 (App. Ct. Ill. 2019)

Case (cite)
People v. Marchan, 2019 WL 4915457 (App. Ct. Ill. 2019)
Type of proceeding
Type of claim
Evidentiary; Ineffective assistance of counsel
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
Angela Horn
Summary of reasons for ruling
Defendant argues that the expert did not lay a foundation for her opinions because she did not provide specific details about the characteristics that led her to her conclusion. The court stated that he had properly explained in detail her methods and conclusions, and that Defendant had the opportunity to cross-examine her at length. Further, it is for the jury to decide the weight of the expert's testimony based on their credentials and basis for their opinion. The court also cites to precedent fingerprint case that an expert is not required to testify to the factual basis of their opinion to be admissible.Defendant also alleges ineffective assistance of counsel for failing to object to the expert's testimony, specifically that their opinion was "based upon a forensic certainty." The court holds that the defendant cannot satisfy either prong of the relevant test: (1) at the pre-trial hearing, the court only prevented testimony to a "scientific certainty" but allowed testimony based on training, experience, and background without limit on forensic certainty, and (2) defendant cannot establish that counsel's error prejudiced him because this was not the only evidence against him and her testimony would have only been limited, not excluded, under this standard.
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


Note: In this case, defendant did not question the reliability of the methods used or firearms identification testimony as a whole.




“Specifically, this court has found that Safford’s holding that an expert is required to testify to the factual basis for their expert opinion in order for their testimony to be admissible is an incorrect statement of law, and in fact, the factual basis for an expert’s opinions is a matter for cross-examination. . . . Accordingly, we similarly decline to follow Safford.”