With all of the attention paid to children's performances as witnesses once on the stand, their ability to qualify to take the stand has been relatively neglected. Most courts require that in order to testify, a witness must first take the oath. In its most simple form, an oath is a promise to tell the truth. Taking the oath presupposes that one understands what it means to tell the truth, and that one appreciates one’s obligation to tell the truth when promising to do so. If a young child does not understand the difference between the truth and lies, or fails to appreciate his or her obligation to tell the truth, he or she may be found incompetent, and not allowed to testify. In some jurisdictions, a finding of testimonial incompetence may even render inadmissible the child’s out-of-court statements, which might otherwise be admitted under an exception to the rule against hearsay (e.g. Oldsen v. Colorado, 1987).