Evidence question re Rule 104 Forum

[MoltenWings]

I am having trouble understanding Rule 104(a) and (b). Specifically, I fail to understand when 104(a) would apply, as opposed to 104(b), and vice versa. I also fail to see why it is significant. Help please...

[Tanicius]

It's a pretty loose distinction to be honest. Basically, I would look at like this: When a piece of evidence only matters when it relies on an underlying premise being true, and you dispute the underlying premise, then it's only conditionally relevant.

[Oglethorpe]

I am having trouble understanding Rule 104(a) and (b). Specifically, I fail to understand when 104(a) would apply, as opposed to 104(b), and vice versa. I also fail to see why it is significant. Help please...

104(a) and (b) are both rules dealing with the standard of admissibility of evidence. Obviously, the judge is the gatekeeper of evidence. All evidence must pass FRE 104. 104(b) supplies the standard for conditional evidence. Conditional evidence is evidence that is only relevant if another fact is proved. For example, Prosecutor's theory is that D killed V because V agreed to testify against D. The fact that V agreed to testify against D is only relevant if D knew that V agreed to testify against D. Thus, the fact that V agreed to testify against D is conditional, and subject to the standard set forth in FRE 104(b): the proponent must introduce evidence sufficient that a reasonable jury could find the conditioned fact by a preponderance of the evidence. In other words, the prosecutor must introduce evidence sufficient to prove that a reasonable jury could find that D knew that V had agreed to testify against D. This standard is less burdensome than 104(a).

104(a) governs the admissibility of all other evidence. Here, the trial judge decides whether the evidence gets in by a preponderance of the evidence. For example, if the proponent seeks to admit hearsay evidence under an exception, the judge must decide that the elements of the hearsay exception have been satisfied by a preponderance of the evidence.

The difference is subtle, but important. "A reasonable jury could find"... vs "the trial judge finds by a preponderance of the evidence."