In the case Breed vs. Jones, the U.S. Supreme Court determined that trying a person in adult court after they are tried in juvenile court constitutes double jeopardy. The decision came from the Supreme Court in 1975.
In 1971, Gary Jones was charged with armed robbery at the age of 17. A detention hearing, also known as adjudication, took place and it was ordered that he be detained. After the judge had given the case to the adult criminal court system, attorneys for Jones filed a writ of habeas corpus claiming this violated the double jeopardy clause as outlined in the Fifth Amendment. The judge disagreed and denied the petition on the grounds that Jones was not tried twice since juvenile adjudication is not officially a trial; therefore, it was not double jeopardy. After the case was brought to the Supreme Court, it was ruled that adjudication in the juvenile court system is equal to a criminal trial and does constitute double jeopardy.