What is Jeopardy?
Jeopardy, in law, is the state of being in danger of conviction and punishment for committing a crime. A person is usually considered to be in jeopardy when, after a proper indictment, a trial jury has been impaneled and testimony has begun. Most modern legal systems prohibit double jeopardy, or the subjecting of a person to two trials for the same crime. However, there are some necessary exceptions to the rule against double jeopardy. For example, if the judge becomes ill during the trial or if the jury is unable to agree on a verdict, a mistrial will be declared and the case may be retried later. Also, after sentence has been pronounced, either side in a criminal trial can appeal to a higher court for retrial.
In civil actions the concept of res judicata is similar to the prohibition of double jeopardy. It means that once a matter has been settled by a court of law, it cannot be reopened.