The history of the mixed jury for aliens begins in the early Fourteenth Century with Gascon wine merchants. On 30 August 1302, in exchange for some financial help to the king, they were given the privilege to a half Gascon jury in all cases except felony. The duchy of Gascony was ruled by the English king and granting this to his Gascon subjects could be seen as nothing more than enforcing the ‘judgment by peers’ rule laid down in Magna Carta. However, other alien merchants soon obtained the same privilege. After some lobbying by German merchants, the half-alien jury was extended to all alien merchants on 1 February 1303 by the Carta Mercatoria. A half-alien jury was also to be summoned in cases where both parties were foreigners. One might suspect that this would make it more difficult to reach a verdict because there was no requirement that the alien jurors had to be fellow countrymen of the parties. In practice, however, they were chosen from men who came from the same region.
The ‘right’ to a half-alien jury was a privilege granted by the king. This means that it had to be requested by the party to a lawsuit and was not given as a matter of course. It also meant that it could be taken away. It was therefore important for the alien merchants to make use of the privilege on a regular basis.
Opposition to the mixed jury for alien merchants was there from the beginning. One argument, put forward by the king’s attorney, was that it was impossible to get impartial alien jurors because the outcome of a lawsuit would affect all (which could be true only for a limited number of cases). Other parties tried to limit the mixed jury to lawsuits which were connected with fairs and markets.
However, despite the opposition, the mixed jury was unstoppable. In 1354 a statute was enacted extending the mixed jury to all aliens (not just merchants) and to all cases, including felony. Although the privilege was now statutory, mixed juries still had to be requested by the parties. It was also ruled that in an all-alien lawsuit an English jury was to be summoned (the only exception being lawsuits heard before the Mayor of the Staple).
Mixed juries were requested by aliens throughout the Fourteenth and Fifteenth Centuries. In the middle of the Fifteenth Century we begin to find requests for a half-tongue jury, that is to say a jury where linguistic rather than geographical commonality was stressed. Alien jurors would be chosen from the same region but not necessarily from the same town as the party, but by the end of the Fifteenth Century we find aliens from various regions and countries serving as jurors. There was no requirement that they had to have the same ethnic background as the parties involved in the lawsuit. Alien jurors were subject to the same rules about jury qualification as native jurors.
For further discussion see Susanne Jenks, ‘Justice for Strangers: the Experience of Alien Merchants in Medieval English Common Law Courts’, in The Medieval Merchant. Proceedings of the 2012 Harlaxton Symposium, ed. by Caroline M. Barron and Anne F. Sutton (Harlaxton Medieval Studies, XXIV), Shaun Tyas, Donington 2014, pp. 166-182.