Definition - What does Witness Tampering mean?
Witness tampering is a crime that sees a witness in a court action intimidated, bribed, threatened, or harassed in an effort to get them to change their story. Courts attempt to ensure that the evidence that is brought before a court is true and any attempt to deride the courts' abilitiy to hear the full facts of the case brought by a witness will be dealt with as witness tampering.
Justipedia explains Witness Tampering
Sometimes courts will keep witnesses under protection or in custody until they give evidence in order to ensure that witness tampering does not happen. There are times that a witness willingly agrees to change their evidence such as when they are bribed and other times where they are under duress of a threat to self or on a member of their family.