State v. Lehr
201 Ariz. 509, 38 P.3d 1172, 378 Ariz. Adv. Rep. 6 (2002)
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Rule of Law:
A criminal defendant's Sixth Amendment right to confront adverse witnesses is violated when a trial court prohibits cross-examination and expert testimony regarding the reliability of a scientific methodology, even if that methodology was previously deemed admissible in a pretrial hearing. While judges determine the admissibility of evidence, juries must be allowed to hear challenges relevant to the weight and credibility of that evidence to properly perform their fact-finding function.
Facts:
- Over the course of approximately one year, Scott Alan Lehr allegedly engaged in a series of attacks against ten different women.
- The attacks followed a pattern where Lehr would offer a ride to a woman, drive her to a remote desert area north of Phoenix, and sexually assault her.
- In several instances, the assaults involved choking the victims into unconsciousness or beating them with rocks.
- Three of the victims, M.C., B.C., and M.M., were killed by blunt force trauma to the head, and their bodies were left in desert or rural areas.
- Police recovered physical evidence linking Lehr to several of the attacks, including DNA samples from four victims (W.C., J.T., M.C., E.R.), his fingerprint at one scene, and a ring belonging to victim B.C. in his home.
- Lehr was a tree-trimmer familiar with the desert areas where the attacks occurred.
- When questioned, Lehr denied ever meeting any of the victims and offered alternative explanations for the evidence, such as having bought the ring at a garage sale.
Procedural Posture:
- Scott Alan Lehr was charged in Arizona state trial court with multiple counts of murder, sexual assault, and other felonies related to attacks on ten victims.
- The trial court consolidated the case with others for a pretrial Frye hearing to determine the admissibility of DNA evidence from the Department of Public Safety (DPS) lab.
- Following the hearing, the judge ruled that the DPS lab's RFLP protocol met the general acceptance test and that the DNA evidence was admissible.
- The defense moved to sever the charges, and the trial court separated the case into a capital trial for three homicides and four sexual assaults, and a non-capital trial for three other sexual assaults.
- The prosecution moved to preclude the defense from cross-examining state DNA experts at the capital trial on issues related to the lab's protocol and validation studies, arguing those matters were settled by the Frye ruling.
- The trial judge granted the prosecution's motion, limiting the scope of cross-examination to case-specific errors.
- Following trial, the juries returned guilty verdicts on numerous counts in both trials, and Lehr was ultimately sentenced to death for the murder convictions.
- Lehr filed a direct appeal of his convictions and sentences to the Supreme Court of Arizona.
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Issue:
Does a trial court's preclusion of cross-examination regarding the reliability of a scientific laboratory's protocol and validation studies, which were previously deemed admissible in a pretrial Frye hearing, violate a criminal defendant's Sixth Amendment right to confront adverse witnesses?
Opinions:
Majority - Zlaket, Justice
Yes. A trial court's blanket preclusion of cross-examination concerning the underlying reliability of an admitted scientific methodology violates a defendant's Sixth Amendment right to confront adverse witnesses. The court distinguished between the admissibility of evidence, which is a preliminary question for the judge, and the weight and credibility of that evidence, which is a matter for the jury. A pretrial Frye hearing determines only admissibility; it does not foreclose a defendant's right to challenge the reliability and credibility of the evidence before the jury. The trial court erroneously assumed that allowing cross-examination on the DPS lab's protocol would improperly ask the jury to 'relitigate' the Frye ruling. This infringed upon the jury's role and improperly shielded the state's most critical evidence from challenge. This constitutional error was not harmless for the convictions involving victims M.C., W.C., and M.M., where DNA evidence was the only significant evidence linking Lehr to the crimes, and therefore those convictions must be reversed.
Analysis:
This case reinforces the fundamental distinction between the judge's gatekeeping role in admitting scientific evidence and the jury's fact-finding role in weighing it. The decision clarifies that a favorable ruling in a pretrial Frye or Daubert hearing does not grant scientific evidence an irrebuttable presumption of credibility at trial. By affirming the defendant's right to cross-examine experts on foundational issues like lab protocols and validation studies, the court ensures that the jury can fully assess the reliability of such powerful evidence. This precedent limits a trial court's discretion to restrict cross-examination on scientific methodology and safeguards against jurors being unduly swayed by an 'aura of infallibility' surrounding expert testimony.
