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Law 101: Legal Guide for the Forensic Expert


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

A typical motion at trial is for all witnesses to be sequestered, that is, to be kept out of the courtroom while all other evidence is presented. The theory of sequestration is simple: By isolating the witnesses, no witness will hear the questions posed and answers given by others, or attempt to conform to the others' testimony.

A typical sequestration order directs the witnesses to remain out of the courtroom and not to discuss their testimony with others until the trial has concluded.

There are exceptions to the order of sequestration. In many jurisdictions, the case agent or lead investigator is permitted to remain in the courtroom throughout the trial, even though the investigator will also have a role as a testifying witness.

In some cases, judges will permit expert witnesses to remain during the testimony of others — as experts are permitted to comment on facts adduced from other witnesses — and to address the contentions of opposing experts.

Finally, the accused person in a criminal trial is never subject to a sequestration order, as criminal defendants have the constitutional right to be confronted by the witnesses against them.

There is no fixed rule that sets consequences for the violation of a sequestration order. Courts consider whether the violation was inadvertent or intentional, and the extent and duration of the violation. Consequences may range from an instruction, telling jurors to be aware of the violation when deciding the case, to the extreme sanctions of witness preclusion and contempt citations.

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