This section is from the book "Popular Law Library Vol1 Introduction To The Study Of Law Legal History", by Albert H. Putney. Also see: Popular Law-Dictionary.
The most fundamental characteristic of the English common law, on both its civil and criminal side, is that of trial by jury. Although the pride of the English race, this legal institution is not of indigenous growth. Many origins for the jury have been suggested but the probabilities are that it is an outgrowth of the Frankish Inquest. The members of the Frank-ish Inquest, and of the early jury, were men who were supposed to be in a position to judge from their own knowledge as to the truth of the controversy. They combined within themselves the dual character of witnesses and judges. Trial by inquest became the method of trial in the four so-called petty assizes (Utrum, disseisin, mort d'ancestor, and darrein presentment) .
" Trial by jury, in the narrowest sense of that term, trial by jury as distinct from trial by an assize, slowly creeps in by another route. The principle from which it starts is simply this, that if in any action the litigants by their pleadings come to an issue of fact, they may agree to be bound by the verdict of a jury, and will be bound accordingly. In course of time the judges will in effect drive litigants into such agreements by saying 'You must accept your opponent's offer of a jury or you will lose your cause;' but in theory the jury only comes in after both parties have consented to accept its verdict."10
The right of trial by jury was for a long time confined to certain forms of action; in other forms the wager of law and the wager of battle were permitted even as far down as the nineteenth century. This state of affairs largely accounts for the disappearance of certain actions and the growth of others. The old forms which still permit the wager of law and the wager of battle become obsolete and the newer forms which carry with them the jury trial take their place.