What is the test for cross-examination under the Sixth Amendment?

Respondent relies upon Dutton v. Evans (1970) 400 U.S. 74, 91 S.Ct. 210, 27 L.Ed.2d 213 to which we now address ourselves. We recognize preliminarily that a hearsay statement which subjects the declarant 'to the risk of . . . criminal liability' may for that reason well be presumed to be true because 'a reasonable man in his position would not have made the statement unless he believed it to be true'. (Evid.Code, 1230.) But, the fact that a statement is true does not satisfy the constitutional requirement of confrontation and the right of cross-examination. Truth is only one element of a witness's testimony. Every witness takes an oath to tell not only the truth, but the Whole truth and Nothing but the truth. The great value of cross-examination is that it affords an opportunity for the trier of fact to determine not only that the witness has testified truthfully, but that he has told the whole story and that he has not included anything which is untrue. Experience teaches every trial judge and trial lawyer that the addition of one omitted fact may well change the complexion of the entire story or the exclusion of one included fact which is untrue or partially misrepresented may likewise change the complexion of the entire story. The Whole truth is sometimes critically different from a Partial truth. The fact that an extra-judicial statement may be given under circumstances (such as being against penal interests) which make it probable that it is true does not for that reason automatically satisfy the constitutional right of confrontation. Only cross-examination can establish whether a true statement which satisfies the requirements of Evidence Code section 1230 is the Whole truth and Nothing but the truth. That, we believe, is the rationale behind the Sixth Amendment.