jeopardy, in law, condition of a person charged with a crime and thus in danger of punishment. At common law a defendant could be exposed to jeopardy for the same offense only once; exposing a person twice is known as double jeopardy. Double jeopardy is prohibited in federal and state courts by the Fifth and Fourteenth Amendments to the U.S. Constitution. The concept refers to an offense, not to an act giving rise to an offense; therefore, it is possible to try a person for multiple violations arising from a single act (e.g., assault, attempted murder, and carrying a deadly weapon). Jeopardy does not exist until the jury is sworn in, or, if there is no jury, until evidence is introduced. The prohibition of double jeopardy does not preclude a second trial if the first court lacked jurisdiction (authority), if there was error in the proceedings, or if the jury could not reach a verdict. A similar principle, known as res judicata, operates in civil suits. It holds that once a civil case has been finally decided on the merits the same parties can not litigate it again. In England and Wales, revisions to criminal law that took effect in 2005 now permit the Court of Appeal to order a person acquitted of a crime to be retried if there is "new and compelling" evidence.