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Law 101: Legal Guide for the Forensic Expert

Pretrial Motions

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National Institute of Justice (NIJ) (see reuse policy).

Some evidence may be subject to challenge. For example, it may:

  • Be novel scientific evidence (i.e., not widely accepted by the scientific community).
  • Carry a risk of unfair prejudice.
  • Involve hearsay (some, but not all, of which is inadmissible).

See Key Issues in Reference to Hearsay. Also see Federal Rules of Evidence Regarding Hearsay.

Skilled prosecutors and defense attorneys know that the time to resolve such admissibility issues is before trial, not in a fight in front of the jury.

The mechanism used to resolve such disputes is a motion in limine. The party seeking to either ensure admission or bar use of an item of evidence will file such a motion, identifying the evidence at issue and setting forth the legal arguments governing admissibility.

Judges may decide the issue solely on the basis of motion papers submitted and any written responses from the opposing attorney after hearing oral argument from both sides. In some cases, the judge may refrain from ruling and wait to see how the trial develops and whether the challenged evidence is appropriate in light of other trial proof.


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