What is the effect of relying solely on an out-of-court statement made by a legally incompetent minor in a sexual assault case?

In concluding that the corroboration requirement is inapplicable, we emphasize the importance of juvenile court scrutiny of the statements of young children who are both legally incompetent and insulated from cross-examination. At least in the case of a truth incompetent minor, the court may rely exclusively on these out-of-court statements only "if the declarant's truthfulness is so clear from the surrounding circumstances that the test of cross-examination would be of marginal utility...." (Idaho v. Wright, supra, 497 U.S. at p. 820, 110 S.Ct. 3139.)⁷