Com. v. Vilayphanh, O., 2751 EDA 2023

Oudeom Vilayphanh was convicted of third-degree murder, possession of an instrument of a crime, and two counts of aggravated assault after shooting his brother, injuring his father, and firing at police in his parents’ Philadelphia home.
Vilayphanh’s defense was based on imperfect self-defense, asserting he acted during a PTSD-triggered dissociative state after drinking and taking prescription medication, believing intruders threatened his family.
Prosecution contended Vilayphanh's actions stemmed from an alcohol and prescription drug-induced blackout, not a dissociative mental state.
Competing expert testimony was offered: the defense’s psychologist supported PTSD/dissociation, while the Commonwealth’s psychiatrist found the behavior more consistent with intoxication.
During cross-examination, the trial court barred defense counsel from using a co-counsel’s contemporaneous notes to impeach the Commonwealth’s expert, holding this would violate ethical rules and noting defense counsel did not properly request to introduce the notes or have co-counsel testify.
Vilayphanh appealed, claiming that the trial court’s limitation denied him a fair trial and the constitutional right to present a defense, but the trial court found the issue was waived as defense counsel did not preserve it during trial.

Issue	Plaintiff's Argument	Defendant's Argument	Held
Whether exclusion of co-counsel's notes for cross-examination of Commonwealth's expert violated Vilayphanh’s right to present a defense	Vilayphanh: Excluding the notes unfairly prevented impeaching the expert’s credibility, denying a fair trial; the notes were admissible to challenge impartiality and accuracy	Commonwealth: Defense failed to properly object or move to introduce the notes or testimony; waiver for failure to preserve issue	Issue was waived; defense did not preserve objection or seek proper procedural remedies, so appellate court would not review

Commonwealth v. Berrios, 297 A.3d 798 (Pa. Super. 2023) (issues not raised in the trial court are waived on appeal, including constitutional issues)
Commonwealth v. Thomas, 194 A.3d 159 (Pa. Super. 2018) (timely and specific objections are required to preserve evidentiary issues for appellate review)