Further proof usually consists of affidavits made by the asserted proprietors of the goods, in which they are sometimes joined with their clerks, and others acquainted with the real transactions, and with the real property of the goods claimed. In corroboration of these affidavits, may be annexed the original correspondence, duplicates of bills of lading, invoices, extracts from books, &c. These papers must be proved by affidavits of persons who can speak of their authenticity; and if copies or extracts, they should be collected and certified by public notaries. The affidavits are sworn before magistrates, or others competent to administer oaths in the country where they are made, and authenticated by a certificate from the British Consul. The degree of proof required depends upon the degree of suspicion or doubt that belongs to the case. In case of heavy suspicion and great importance, the court may order what is called "plea and proof," that is, instead of admitting affidavits and documents introduced by the claimant only, each party is at liberty to allege, in regular pleadings, such circumstance as may tend to acquit or condemn the capture, and to examine witnesses in support of the allegation, to whom the opposite party may administer interrogatories. The depositions of the witnesses are taken in writing. If the witnesses are to be examined abroad, a commission issues for that purpose; but in no case is it necessary for them to come to England. These solemn proceedings are seldom resorted to. Standing Commissions may be sent to any neutral country for the general purpose of receiving examinations of witnesses, in all cases where the court may find it necessary, for the purposes of justice, to decree an enquiry to be conducted in that manner.[100] [Sidenote: Prize Jurisdiction.] The Jurisdiction over Prizes is exercised by the Judge of the Admiralty, exclusively of every other judicature of the kind, except in cases of appeal. This Jurisdiction in matter of Prize, (whether it is coeval with the Court of Admiralty, or, which is much more probable, of a later institution, beyond the time of memory,) though exercised by the same person, is quite distinct in its nature. The Judge of the Admiralty is appointed by a commission under the great seal, which enumerates particularly, as well as generally, every object of his jurisdiction, but not a word of prize. To constitute that authority, in every war, a commission under the great seal issues to the Lord High Admiral to will and require the Court of Admiralty, and the Lieutenant and Judge of the said court, his surrogate or surrogates, and they are thereby authorised and required to proceed upon all and all manner of captures, seizures, prizes, and reprisals, of all ships and goods that are or shall be taken, and to hear and determine according to the Courts of Admiralty and the Law of Nations. A warrant issues to the judge accordingly.