Magna Carta for sale

It is a single parchment sheet, filled with handwritten medieval Latin and dotted with a fragmentary royal seal resembling a chewed toffee. But it is one of the most important documents in the world — a 13th-century copy of the Magna Carta, the English legal document enshrining the rights of the individual against the state.

The hallowed parchment goes on view Friday at Sotheby's and will be auctioned on December 18. Estimated to sell for between $20 million and $30 million, it is the only privately owned copy of the Magna Carta, and its owner is the one-time presidential candidate Ross Perot. The other 16 copies in existence are in public collections in Britain and Australia. As a result, this is likely to be the only time the Magna Carta will ever be on the market.

"When looking at when our rights began, it's back to the Magna Carta," Sotheby's vice chairman, David Redden, said. "It makes the ideas of freedom and democracy much more tangible because you can point to the document where they started."

In June 1215, King John assented to the Magna Carta — Latin for "Great Charter"— in Runnymede, a meadow on the banks of the River Thames outside London, in order to pacify his rebellious barons. The charter's declaration that "No free man shall be taken or imprisoned ... except by the lawful judgment of his peers or by the law of the land" set lasting precedents for the right to trial, trial by jury, and the presumption of innocence. King John died three months after he signed the Magna Carta but the charter was confirmed in revised versions in 1216, 1217, and 1225.

Copies of the Magna Carta were widely distributed throughout England but few have survived. Four of the original 1215 issue remain; two are kept in the British Library and one each in Salisbury and Lincoln cathedrals. The Magna Carta entered the British statute book in 1297, and it is this issue of the charter that Sotheby's is selling. "This is the most important version, the one that entered English law," Mr. Redden said.