DEFENDANT ALLEGED HIS ATTORNEY DELIBERATELY WITHHELD IMPEACHMENT EVIDENCE ABOUT AN EXPERT WITNESS WHEN HIS ATTORNEY PERSUADED HIM TO HIRE THE EXPERT; BECAUSE OF THE IMPORTANCE OF THE EXPERT’S TESTIMONY, A HEARING ON DEFENDANT’S MOTION TO VACATE HIS CONVICTION ON INEFFECTIVE-ASSISTANCE GROUNDS SHOULD HAVE BEEN HELD; MATTER REMITTED (THIRD DEPT).

The Third Department, reversing County Court, determined County Court should have held a hearing on defendant’s motion to vacate the judgment of conviction on ineffective-assistance grounds. Defendant alleged his attorney, Mary Rain, deliberately withheld impeachment information about an expert witness, Baerthlein, when persuading defendant to hire the expert:

… [D]efendant’s claim is that Rain was ineffective because she deliberately withheld impeachment evidence about Baerthlein when she persuaded defendant to hire him as an expert and the sole defense witness; that same impeachment evidence was ultimately used to vitiate Rain’s chosen defense; and that defendant would not have retained Baerthlein if Rain had disclosed the evidence in the first place. Given the central importance of Baerthlein’s credibility — particularly “in a case such as this, where casting doubt on the prosecution’s medical proof is the crux of the defense” … — Rain’s alleged failures, if true, were not the product of a legitimate but ill-advised trial strategy … . People v Thornton, 2026 NY Slip Op 03699, Third Dept 6-11-26

Practice Point: Here the allegation defense counsel deliberately withheld impeachment evidence about an expert witness while persuading defendant to hire the expert raised a factual question which required a hearing re: defendant’s motion to vacate his conviction on ineffective-assistance grounds.