Blackstone's Commentaries on the Laws of England, book 3 ("Of Private Wrongs"), chapter 22 ("Of the Several Species of Trial"), section 5:
The next species of trial is of great antiquity, but much disused; though still in force if the parties choose to abide by it: I mean the trial by wager of battle. This seems to have owed its original to the military spirit of our ancestors, joined to a superstitious frame of mind; it being in the nature of an appeal to Providence, under an apprehension and hope (however presumptuous and unwarrantable) that heaven would give the victory to him who had the right. The decision of suits, by this appeal to the God of battles, is by some said to have been invented by the Burgundians, one of the northern or German clans that planted themselves in Gaul. And it is true, that the first written injunction of judiciary combats that we meet with, is in the laws of Gundobald, A.D. 501, which are preserved in the Burgundian code. Yet it does not seem to have been merely a local custom of this or that particular tribe, but to have been the common usage of all those warlike people from the earliest times. And it may also seem from a passage in Velleius Paterculus, that the Germans, when first they became known to the Romans, were wont to decide all contests of right by the sword: for when Quinctilius Varus endeavoured to introduce among them the Roman laws and method of trial, it was looked upon (says the historian) as a "novitate incognitae ... et solita armis discerni jure terminarentur". And among the ancient Goths in Sweden we find the practice of judiciary duels established upon much the same footing as they formerly were in our own country.
This trial was introduced into England among other Norman customs by William the conqueror; but was only used in three cases, one military, one criminal, and the third civil. The first in the court-martial, or court of chivalry and honour: the second in appeals of felony, of which we shall speak in the next book: and the third upon issue joined in a writ of right, the last and most solemn decision of real property. For in writs of right the jus proprietatis, which is frequently a matter of difficulty, is in question; but other real actions being merely questions of the jus possessionis, which are usually more plain and obvious, our ancestors did not in them appeal to the decision of providence. Another pretext for allowing it, upon these final writs of right, was also for the sake of such claimants as might have the true right, but yet by the death of witnesses or other defect of evidence be unable to prove it to a jury. But the most curious reason of all is given in the mirror, that it is allowable upon warrant of the combat between David for the people of Israel of the one party, and Goliath for the Philistines of the other party: a reason, which Pope Nicholas I very seriously decides to be inconclusive. Of battle therefore on a writ of right we are now to speak; and although the writ of right itself, and of course this trial thereof, be at present disused; yet, as it is law at this day, it may be matter of curiosity, at least, to enquire into the forms of this proceeding, as we may gather them from ancient authors.
The last trial by battle that was joined in a civil suit (though there was afterwards one in the court of chivalry in the reign of Charles the First; and another tendered, but not joined, in a writ of right upon the northern circuit in 1638) was in the thirteenth year of Queen Elizabeth, as reported by Sir James Dyerr, and was held in Tothill fields Westminster, "non sine magna juris consultorum perturbatione," said Sir Henry Spelmans, who was himself a witness of the ceremony. The form, as appears from the authors before cited, is as follows.
When the tenant in a writ of right pleads the general issue, viz. that he has more right to hold, than the demandant has to recover; and offers to prove it by the body of his champion, which tender is accepted by the demandant; the tenant in the first place must produce his champion, who, by throwing down his glove as a gage or pledge, thus wages or stipulates battle with the champion of the demandant; who, by taking up the gage or glove, stipulates on his part to accept the challenge. The reason why it is waged by champions, and not by the parties themselves, in civil actions, is because, if any party to the suit dies, the suit must abate and be at an end for the present; and therefore no judgment could be given for the lands in question, if either of the parties were slain in battle: and also that no person might claim an exemption from this trial, as was allowed in criminal cases, where the battle was waged in person.
A piece of ground is then in due time set out, of sixty feet square, enclosed with lists, and on one side a court erected for the judges of the court of common pleas, who attend there in their scarlet robes; and also a bar is prepared for the learned serjeants at law. When the court sits, which ought to be by sunrising, proclamation is made for the parties, and their champions; who are introduced by two knights, and are dressed in a suit of armour, with red sandals, barelegged from the knee downwards, bareheaded, and with bare arms to the elbows. The weapons allowed them are only batons, or staves, of an ell long, and a four-cornered leather target; so that death very seldom ensued this civil combat. In the court military indeed they fought with sword and lance, according to Spelman and Rushworth; as likewise in France only villains fought with the buckler and baton, gentlemen armed at all points. And upon this, and other circumstances, the president Montesquieu has with great ingenuity not only deduced the impious custom of private duels upon imaginary points of honour, but has also traced the heroic madness of knight errantry, from the same original of judicial combats. But to proceed.
When the champions, thus armed with batons, arrive within the lists or place of combat, the champion of the tenant then takes his adversary by the hand, and makes oath that the tenements in dispute are not the right of the demandant; and the champion of the demandant, then taking the other by the hand, swears in the same manner that they are; so that each champion is, or ought to be, thoroughly persuaded of the truth of the cause he fights for. Next an oath against sorcery and enchantment is to be taken by both the champions, in this or a similar form; "hear this, ye justices, that I have this day neither eat, drank, nor have upon me, neither bone, stone, ne grass; nor any enchantment, sorcery, or witchcraft, whereby the law of God may be abased, or the law of the devil exalted. So help me God and his saints."
The battle is thus begun, and the combatants are bound to fight till the stars appear in the evening: and, if the champion of the tenant can defend himself till the stars appear, the tenant shall prevail in his cause; for it is sufficient for him to maintain his ground, and make it a drawn battle, he being already in possession: but, if victory declares itself for either party, for him is judgment finally given. This victory may arise, from the death of either of the champions: which indeed has rarely happened; the whole ceremony, to say the truth, bearing a near resemblance to certain rural athletic diversions, which are probably derived from this original. Or victory is obtained, if either champion proves recreant, that is, yields, and pronounces the horrible word of craven; a word of disgrace and obloquy, rather than of any determinate meaning. But a horrible word it indeed is to the vanquished champion: since as a punishment to him for forfeiting the land of his principal by pronouncing that shameful word, he is condemned, as a recreant, amittere liberam legem, that is, to become infamous and not be accounted liber et legalis bono; being supposed by the event to be proved forsworn, and therefore never to be put upon a jury or admitted as a witness in any cause.
This is the form of a trial by battle; a trial which the tenant, or defendant in a writ of right, has it in his election at this day to demand; and which was the only decision of such writ of right after the conquest, till Henry the Second by consent of Parliament introduced the grand assizes, a peculiar species of trial by jury, in concurrence therewith; giving the tenant his choice of either the one or the other. Which example, of discountenancing these judicial combats, was imitated about a century afterwards in France, by an edict of Louis the Pious, A.D. 1260, and soon after by the rest of Europe. The establishment of this alternative, Glanvil, Chief Justice to Henry the Second, and probably his adviser herein, considers as a most noble improvement, as in fact it was, of the law.
Blackstone's Commentaries on the Laws of England, book 4 ("Of Public Wrongs"), chapter 27 ("Of Trial, And Conviction"), section 3:
The trial by battle, duel, or single combat: which was another species of presumptuous appeals to Providence, under an expectation that heaven would unquestionably give the victory to the innocent or injured party. The nature of this trial in cases of civil injury, upon issue joined in a writ of right, was fully discussed in the preceding book: to which I have only to add, that the trial by battle may be demanded at the election of the appellee, in either an appeal or an approvement; and that it is carried on with equal solemnity as that on a writ of right: but with this difference, that there each party might hire a champion, but here they must fight in their proper persons. And therefore if the appellant or approver be a woman, a priest, an infant, or of the age of sixty, or lame, or blind, he or she may counterplead and refuse the wager of battle; and compel the appellee to put himself upon the country. Also peers of the realm, bringing an appeal, shall not be challenged to wage battle, on account of the dignity of their persons; nor the citizens of London, by special charter, because fighting seems foreign to their education and employment. So likewise if the crime be notorious; as if the thief be taken with the mainour, or the murderer in the room with a bloody knife, the appellant may refuse the tender of battle from the appellee; for it is unreasonable that an innocent man should stake his life against one who is already half-convicted.
The form and manner of waging battle upon appeals are much the same as upon a writ of right; only the oaths of the two combatants are vastly more striking and solemn. The appellee, when appealed of felony, pleads not guilty, and throws down his glove, and declares he will defend the same by his body: the appellant takes up the glove, and replies that he is ready to make good the appeal, body for body. And thereupon the appellee, taking the book in his right hand, and in his left the right hand of his antagonist, swears to his effect. "Hoc audi, homo, quem per manum teneo," &c: "hear this, O man whom I hold by the hand, who callest thyself John by the name of baptism, that I, who call myself Thomas by the name of baptism, did not feloniously murder thy father, William by name, nor am any way guilty of the said felony. So help me God, and the saints; and this I will defend against thee by my body, as this court shall award." To which the appellant replies, holding the Bible and his antagonist's hand in the same manner as the other: "hear this, O man whom I hold by the hand, who callest thyself Thomas by the name of baptism, that thou art perjured; because that thou feloniously didst murder my father, William by name. So help me God and the saints; and this I will prove against thee by my body, as this court shall award." The battle is then to be fought with the same weapons, viz. batons, the same solemnity, and the same oath against amulets and sorcery, that are used in the civil combat: and if the appellee be so far vanquished, that he cannot or will not fight any longer, he shall be adjudged to be hanged immediately; and then, as well as if he be killed in battle, Providence is deemed to have determined in favour of the truth, and his blood shall be attainted. But if he kills the appellant, or can maintain the fight from sunrising till the stars appear in the evening, he shall be acquitted. So also if the appellant becomes recreant, and pronounces the horrible word of craven, he shall lose his liberam legem, and become infamous; and the appellee shall recover his damages, and also be for ever quit, not only of the appeal, but of all indictments likewise for the same offence.
[I told you, but did you listen? No.]