Rule of Evidence 104(b) can be confusing and easy to forget. Professor Colin Miller has written about this rule and helped clarify it for me.
In a recent SC Court of Appeals case, the court had to determine if text messages were properly allowed into evidence. The text messages allegedly involved the defendant's phone and the State argued that the messages were sent by the defendant. The defendant claimed that they lost the phone previously. The trial court held a preliminary hearing to determine if the defendant sent the text messages.
This preliminary hearing falls under SCRE 104(b), where the relevancy of a piece of evidence depends on the fulfillment of another condition. In this example, the text message is relevant if it was sent by the defendant (and nonhearsay). But if the defendant did not send it, then they wouldn't be relevant. (*this is a very brief summary of the facts and there are many other issues*)
So who determines if the defendant sent it? The US Supreme Court has held:
The court simply examines all the evidence in the case and decides whether the jury could reasonably find the conditional fact...by a preponderance of the evidence.
Huddleston v. United States, 485 U.S. 681, 690, 108 S. Ct. 1496, 1501, 99 L. Ed. 2d 771 (1988)
In this case, the court explained what the trial court did: