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Law 101: Legal Guide for the Forensic Expert

Motion to Suppress

A party may move to suppress the use of a piece of evidence, an expert or a deposition. This motion is normally made if the use of the person or object under question would be invalid or would cause prejudice that would outweigh its value in court or to the jury.

Motions to suppress evidence are generally based on constitutional grounds, citing that the evidence, though relevant, was obtained improperly. The constitutional grounds, primarily applicable in criminal actions, help ensure three key provisions:

  1.   Ensure the safeguards of due process.
  2.   Preserve limitations on self-incrimination.
  3.   Provide protections against unreasonable search and seizure.

A potential for prejudice by the jury is often determined by observing an error or irregularity. The motion to suppress must be made promptly after the error or irregularity is noted. The burden of proof rests on the moving party to prove the need to suppress the item of evidence, the deposition or the expert.

This means that the moving party must persuade the court that the value of the evidence is outweighed by the prejudice caused by introduction of the item. If the burden of proof is met, then the court will rule to exclude the evidence before the trial begins.

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