In United States v. Al-Nouri, --- F.3d ---, No. 20-10317 (9th Cir. 2020), the Court explained that a magistrate judge’s denial of bail pending the conclusion of an extradition proceeding could not be directly appealed to the Ninth Circuit.
Instead, "[t]o the extent a magistrate judge has been assigned the Article III power to make bail decisions, either implicitly by custom or expressly by local rules, such decisions may be reviewed de novo by the district court upon application by a party . . . . The district court’s decision would then be a final decision for purposes of § 1291, and is appealable to this court. Further, a potential extraditee may appeal a denial of bail by way of a petition for writ of habeas corpus."
So there you have it. Go to the district court first.
