dissenting.
I respectfully dissent because the principal opinion strays from the well-settled proposition that Strickland,1 prejudice cannot be proven by mere speculation.
The principal opinion concludes that Vaca established prejudice because Dr. Geis’s testimony may have helped him. The principal opinion also admits the doctor’s testimony may have hurt Vaca. This conclusion is admittedly speculative— “While Dr. Geis’ testimony and report may have helped Vaca, it may have also embittered the jury.” In fact, the principal opinion does not conclude that the failure to produce mental health evidence in this case was below the standard of care, but that the failure to consider whether to present mental health evidence was below the standard of care.
For purposes of demonstrating ineffective assistance of counsel, prejudice must be definite and identifiable. For example, in State v. Kenley, 952 S.W.2d 250, 268 (Mo. banc 1997), the movant alleged counsel was ineffective because he failed to call witnesses to testify as to his mental state at the time he committed the crime. This Court rejected his claim because the testimony the movant claimed would have changed the outcome at trial was speculative:
*338Moreover, Kenley has not proven prejudice. First, as we stated in Section II of this opinion, the testimony of the three medical experts was conflicting and speculative. Each of the three experts had a different theory supporting why Kenley behaved the way he did on the night of the murder.
Id.
In State v. Ferguson, 20 S.W.3d 485, 504 (Mo. banc 2000), the movant alleged counsel was ineffective for failing to plead a Brady violation. This Court found the movant failed to prove prejudice because his claim was “obviously a speculative proposition” in that the undisclosed evidence would not in any way negate his guilt. Id.
In this case, both defense counsel and the sentencing judge, who was also the judge who overruled this post-conviction motion, knew that changing the focus to present this mental health evidence after having defended the case on the basis of a reasonable trial strategy that Vaca was not guilty would have resulted in a harsher, not more lenient, sentence.
I also question whether the circuit court’s determination that defense counsel provided ineffective assistance of counsel was clearly erroneous. The principal opinion’s assumption that there “was no strategic reason” not to present this mental health evidence based solely on defense counsel’s testimony ignores the fact that the circuit court is not required to believe defense counsel’s testimony. Further, the principal opinion’s conclusion that “defense counsel candidly admitted that, without consideration and for no strategic reason, he failed to call a mental health expert” is a mischaracterization of the testimony. Defense counsel’s statement was that “[tjhere was no strategic reason that I can recall for not calling Dr. Geis at sentencing.”
This Court is required to give due regard to the circuit court’s ability to have judged the credibility of the witnesses’ testimony. Rule 84.18(d)(2). Therefore, the circuit court’s finding of fact that defense “counsel pursued reasonable trial strategy regarding his concerns about the movant’s mental competence” is supported by the record and certainly not clearly erroneous.
In addition, the assumption that this mental health evidence would have been admissible at the penalty phase fails to consider § 552.015, RSMo 2000, § 557.086.3, RSMo Supp.2008, and Rule 25.05(1)(2) and (3), which may require a different result.2
I would affirm the motion court’s overruling of Vaca’s Rule 29.15 motion. Vaca has not demonstrated that the result of this proceeding would have been different; therefore, he has failed to prove Strickland’s prejudice requirement.
. Strickland v. Washington, 466 U.S. 668, 687-88, 104 S.Ct. 2052, 80 L.Ed.2d 674 (1984).
. The circuit court concluded as a matter of law:
The report trial counsel obtained from Dr. Geis concerning movant’s mental status did not establish that movant was either incompetent or not guilty by reason of mental disease or defect. Movant did not suffer from a mental disease or defect that qualified as a defense under Chapter 552.
Section 552.015 provides limitations on the admissibility of mental disease or defect evidence.