CALIFORNIA EVIDENCE: CIVIL AND CRIMINAL
...Hearsay Except. Requiring Unavail
......Procedural Aspects of Exceptions
.........Burden of Proving Unavailability
............In General
3 Cards On This Topic:

Unavailability is preliminary fact to be established by proponent of evidence.

Burden of proof to establish unavailability for use of prior testimony is on proponent of evidence; due diligence defined.

Burden is on proponent of evidence to establish declarant's unavailability.