This is why we should never take a written constitution for granted.

For some 800 years, the Common Law of England recognized the defenses of autrefois convict and autrefois acquit. These ancient legal principles respectively prevented retrial for the same offense after a conviction or after an acquittal.

Because of the long history of these twin doctrines as part of the common law, James Madison, the principle author of our Constitution saw no need to provide for such protections in the original document. However, in an apparently prescient move, a majority of the states required these protections and others be included in a "Bill of Rights" as a prerequisite for ratification of the Constitution. Thus, these common law principles became the Double Jeopardy Clause of the Sixth Amendment.

History seems to have proven Madison wrong. On April 4, 2005, the British Parliament abolished these common law prohibitions against double jeopardy and this story in the London Guardian reports on the first case where a defendant is being retried for murder 14 years after he was acquitted of the crime.

Thanks to CrimLaw for the link.