Sixth Amendment--the Confrontation Clause, Witness Memory Loss and Hearsay Exceptions: What Are the Defendant's Constitutional and Evidentiary Guarantees--Procedure or Substance? Claire L. Seltz. 1988. Sixth Amendment--the Confrontation Clause, Witness Memory Loss and Hearsay Exceptions: What Are the Defendant's Constitutional and Evidentiary Guarantees--Procedure or Substance? Journal of Criminal Law & Criminology. 79(3):866-898.