A 13th-century copy of the Magna Carta, a milestone of English freedom, will be offered for sale in New York in December, Sotheby's auction house said Tuesday.

The vellum manuscript owned by the Perot Foundation is estimated to sell for $20 million to $30 million, Sotheby's said.

The document was on display at the National Archives in Washington for more than 20 years until last Thursday.

King John was forced by barons to agree to the charter in 1215. It guaranteed that freemen would not be imprisoned or deprived of property without due process, including a right to a speedy trial before a jury.

Versions of the Magna Carta were issued in 1216, 1217, 1225 and 1264 by John's son, King Henry III.

The copy offered by Sotheby's for sale on Dec. 10 is dated 1297, the year it was incorporated into the statute rolls of King Edward I.

Discovered among the Brudenell family records in England in 1974, the copy is one of only four remaining of the 1297 charter.

H. Ross Perotbought the copy in 1984 and loaned it to the National Archives. It was first exhibited in 1985.