When will a federal writ of habeas corpus ad prosequendum apply to a defendant held in a state's custody?

¹ As we explained in Taylor v. Reno , "[t]he term primary jurisdiction in this context refers to the determination of priority of custody and service of sentence between state and federal sovereigns." 164 F.3d 440, 444 n.1 (9th Cir. 1998). "A lack of primary jurisdiction does not mean that a sovereign does not have jurisdiction over a defendant. It simply means that the sovereign lacks priority of jurisdiction for purposes of trial, sentencing and incarceration." Id .

² A federal writ of habeas corpus ad prosequendum secures the presence for trial of a criminal defendant who is held in a state's custody. United States v. Mauro , 436 U.S. 340, 35758, 98 S.Ct. 1834, 56 L.Ed.2d 329 (1978) ; see also 28 U.S.C. 2241(c)(5) ("The writ of habeas corpus shall not extend to a prisoner unless ... [i]t is necessary to bring him into court to testify or for trial.").