What is the test for unavailability in the constitutional sense when seeking to compel an out-of-state witness to attend a criminal trial?

"[W]hen a criminal trial is at issue, unavailability in the constitutional sense does not invariably turn on the inability of the state court to compel the out-of-state witnesss attendance through its own process, but also takes into consideration the existence of agreements or established procedures for securing a witnesss presence that depend on the voluntary assistance of another government. ( [ Mancusi v. Stubbs (1972) 408 U.S. 204, 211213, 92 S.Ct. 2308, 33 L.Ed.2d 293 ].) Where such options exist, the extent to which the prosecution had the opportunity to utilize them and endeavored to do so is relevant in determining whether the obligations to act in good faith and with due diligence have been met. [Citations.]" ( Herrera, supra, 49 Cal.4th at p. 628, 110 Cal.Rptr.3d 729, 232 P.3d 710, fn. omitted.) However, "when the prosecution discovers the desired witness resides in a foreign nation, and the state is powerless to obtain the witnesss attendance, either through its own process or through established procedures, the prosecution need do no more to establish the

[262 Cal.Rptr.3d 303]