Whether a declarant is 'unavailable to testify' for purposes of the Sixth Amendment

QUESTION PRESENTED FOR REVIEW Whether a declarant is “unavailable to testify” for purposes of the Sixth Amendment, and as that phrase is used in Crawford v. Washington, 541 U.S. 36, 54 (2004), when she is physically present at trial, but states that she does not remember either the events underlying her out-of-court statements or making the statements themselves. i