Extradition.

• Author: Eckholm, Erik
• Position: Amanda Knox

It's spelled out in the U.S. Constitution and in treaties with foreign governments. Five things you should know about what it means for Amanda Knox.

1 What is Amanda Knox charged with?

Six and a half years ago, Amanda Knox, a 20-year-old junior at the University of Washington, spent a semester abroad in Italy. On the morning of Nov. 2, 2007, Knox's house-mate, Meredith Kercher, was found lying dead in their shared apartment in the town of Perugia.

Exactly how that happened and who was responsible has been the source of years of legal wrangling. Knox and her then-boyfriend, an Italian named Raffaele Sollecito, were charged with murder. In 2009, a court in Italy found both guilty. (The court also convicted Rudy Guede, a drug dealer who is now serving a 16-year sentence and who has said Knox was at the scene of the crime.) Knox and Sollecito were imprisoned until October 2011, when an Italian appeals court reversed their convictions, citing a poor police investigation. After her release, Knox went home to Seattle. Sollecito remained in Italy. Last year, Italy's highest court voided the acquittal and ordered a new trial.

Last month that trial concluded, with guilty verdicts once again for Knox and Sollecito; Knox was sentenced to 28 years in prison. They both say they're innocent and will appeal. Knox, now 26, has said she will only return to Italy "kicking and screaming."

2 What is extradition?

Extradition is the transfer of someone accused of a crime from one country (or state) to another for prosecution or punishment. The concept dates back to ancient times: The Roman Empire allowed for extradition between its far-flung provinces. Formal extradition treaties became common in the mid-19th century, when better transportation allowed criminals to more easily escape across borders.

Extradition between states (but not between countries) is mentioned in Article 1V of the U.S. Constitution: "A person charged in any state... who shall flee from justice, and be found in another state, shall on demand of the executive authority of the state from which he fled, be delivered up, to be removed to the state having jurisdiction of the crime."

The first U.S. extradition agreement with a foreign government was a clause in the 1794 Jay Treaty with Great Britain; it applied only to murder and forgery.

3 What countries does the U.S. have extradition treaties with?

Today, Italy is one of more than 100 countries with which the U.S. has extradition treaties (see...