The Magna Carta forced the Barons to pay for the eldest daughter 's wedding , and later sleeping with her was made High Treason , punishable by death - a law only changed in 1998 For instance , according to Magna Carta , aids were due from the barons of the realm to finance the first wedding of the king 's eldest daughter ; and by a statute of the 25th year of King Edward III , sleeping with the king 's eldest daughter before her marriage constitutes an act of high treason punishable by death .