Prosecutors and judges must have guidance on how they can make a child more comfortable so that testimony can more readily be given, since almost half the States stipulate that every person is competent to be a witness. The remaining States prescribe an age, usually 10 or 14 years, below which a child is not presumed competent to testify and thus must be proven competent at a voir dire competency hearing. Courts do not usually allow expert testimony by psychologists and mental health experts on a given child's cognitive, communicative, or memory abilities for the purpose of aiding the court in making a competency determination. The use of psychological expert testimony to aid the court in determining the credibility rather than the competency of a child victim's allegations is particularly controversial. Courts have not been willing to allow psychologists to testify as to their belief that a given child has been truthful or untruthful or that children generally do or do not lie when they claim to have been abused. Most judges will likely place limited merit on expert testimony in abuse cases if the psychologist has been retained by one of the parties to the litigation. Within the area of family law, there is growing recognition of the way the judicial system handles child abuse cases, particularly cases where one parent is accusing the other of sexually molesting the child. In addition, sexual abuse experts indicate that testifying at trial is a frequent fear expressed by many child victims. Solid research is needed on whether the act of testifying causes behavioral disturbances in young children and which children are most vulnerable. Another issue of importance to psychologists involves the admissibility of child victim hearsay statements.