Defense counsel has an obligation to investigate all possible defenses and must not select a strategy without carrying out an adequate investigation. Petitioner was convicted of numerous counts of child molest and sentenced to multiple life terms. The case involved a credibility contest between petitioner, the two alleged victims, one of whom had recanted twice, and the prosecution’s expert witness, a doctor. According to defense counsel’s post-trial declaration, she was provided the medical forensic report but failed to obtain photographs taken during the examination of the victim and did not consult with a medical expert prior to trial. Her trial strategy was to show that the one victim lied when she made her accusations but then told the truth when she recanted and that the second victim lied. According to the post-trial declaration of a medical expert, the testimony of the prosecution’s expert witness was subject to significant impeachment. The appellate court found that by not adequately investigating all possible defenses, i.e., impeachment of the prosecution’s expert witness with a defense medical expert, defense counsel could not make a rational and informed decision on strategy and tactics for trial and, thus, petitioner was denied effective assistance of counsel. Because the case was a credibility contest, if counsel had the assistance of a medical expert, there is a reasonable probability that petitioner would have obtained a more favorable result. Therefore, the petition for writ of habeas corpus was granted, with the convictions reversed.