An alternate juror is a spare, not unlike the spare tire for your car that rides along with you wherever you drive but is only used if one of your regular tires fails. Similarly, an alternate juror sits and listens to evidence just like the other jurors but only deliberates and votes if one of the sitting jury members is unable to serve.
Jurors Are Fact-Finders
Litigation means argument. In criminal cases, a prosecutor argues with the defense attorney over whether the accused is guilty. In civil cases, two or more parties disagree as to who owes whom damages. A judge decides the laws that apply to a particular case, but ordinary men and women, picked at random from the community, sit as the jury to determine the facts of a case. Trial juries are composed of at least six people sworn to decide the facts based on the evidence presented.
Disqualified Jurors Must Be Replaced
The number of jurors in a trial can vary, but the exact number required for a particular case must sit through the entire trial, hear all the evidence and arguments presented, and then determine the facts in dispute. But life intervenes sometimes -- a juror falls ill or behaves so improperly that the judge dismisses him. Without alternate jurors, the entire trial would have to begin again. But an alternate juror who sat through the trial from the beginning can simply take the place of a dismissed or ill juror.
Duties of Alternative Jurors
An alternate juror who might be called upon to move into an empty spot on the jury must follow all the rules that regular jurors follow. She must listen to the evidence presented with an open mind, avoid hearing about the case from outside sources like television and, if called upon to deliberate, make decisions about the facts based only on a fair weighing of the evidence presented at trial by both sides.