Evidence Code section 700 bestows on the trial judge sole authority to determine the competency of a witness to testify and age of the witness is not a per se disqualification. In his combined habeas/direct appeal action, appellant argued that he was denied effective assistance by trial attorney as she did not request a pre-trial hearing to determine the competency to testify of the alleged child victim of the molests. Because the victim was an articulate witness and there was no evidence that she had been influenced to testify falsely, it was reasonable for trial counsel to believe that there would be nothing to gain with a competency hearing as the child would not be disqualified and that the childs testimony could be attacked on cross-examination. As such, appellant was not able to meet the ineffective assistance criteria of Strickland v. Washington (1984) 466 U.S. 668 [104 S.Ct. 2052].