The Signatura is Not the Supreme Court

Over the next few days and weeks, the media will take to describing the Apostolic Signatura as the Vatican's "Supreme Court" but the analogy is not a strong one. The Prefect of the Signatura, Archbishop Raymond Burke, was named a cardinal this morning as expected.
If by "Supreme Court" one means that the Signatura is the highest tribunal in the Vatican, that is true. But, the Signatura is quite different from the U.S. Supreme Court. In the U.S. system, the Supreme Court is an independent branch of government and its members are appointed for life. In the Vatican, the Pope himself holds all legislative, executive and judicial authority. The Pope is the final tribunal at the Vatican, not the Signatura, and its prefect serves at the pleasure of the Pope.