Double Jeopardy
The Constitution prevents a person from being tried more than once for the same crime. Jeopardy does not attach until there is a jury verdict or a dismissal with prejudice by the judge. If there is a mistrial because of attorney misconduct or because the jury cannot reach a verdict, then there is no final ruling and the prosecutor may retry the case. Generally, the prosecutor may only try the defendant once on a given set of facts. If the defendant is found innocent of murder, he or she cannot be retried on the same facts for a lesser included offense such as manslaughter.
Double jeopardy only applies to one level of government. If the state tries a person for murder and the defendant is acquitted, the federal government can retry the person on the same facts, perhaps for civil rights violations. This is a significant problem in medical care because many of the prohibited activities, especially fraudulent transactions, violate both state and federal law.