The practice is regulated in various Germanic legal codes and survived throughout the Viking Age in Scandinavia in the form of the Holmgang. Capitularies governing its use appear from the year 803 onwards (Boretius 1.117). Louis the Pious prescribed combat between witnesses of each side rather than between the accuser and the accused, and briefly allowed for the ordeal of the cross in cases involving clerics.
Although earlier records mention the use of swords, Carolingian law prescribed wooden clubs and shields.
The Sachsenspiegel of 1230 still recognizes the judicial duel as an important function to establish guilt or innocence in cases of insult, injury or theft. The combatants are armed with sword and shield and may wear linen and leather clothing, but their head and feet must be bare and their hands only protected by light gloves. The accuser is to await the accused at the designated place of combat. If the accused does not appear after being summoned three times, the accuser may execute two cuts and two stabs against the wind and his matter will be treated as if he had won the fight (book I, art. 63).
The Kleines Kaiserrecht, anonymous legal code of ca. 1300, prohibits judicial duels altogether, stating that the emperor had come to this decision on seeing that too many innocent men were convicted by the practice just for being physically weak. Nevertheless, judicial duels continued to be popular throughout the 14th and 15th centuries.
Trial by combat plays a significant role in the German schools of fencing in the 15th century. Notably Hans Talhoffer depicts techniques to be applied in such duels, separately for the Swabian (sword and shield) and Franconian (mace and shield) variants, but other Fechtbücher such as that of Paulus Kal and the Codex Wallerstein show similar material. While commoners were required to present their case to a judge before duelling, members of the nobility did have the right to challenge each other for duels without the involvement of the judicative, so that duels of this kind were separate from the judicial duel already in the Middle Ages and were not affected by the latter's abolition in the early 1500s, evolving into the gentlemanly duel of modern times which was outlawed only as late as in the 19th century.
Hans Talhoffer in his 1459 Thott codex names seven offences that were considered grave enough to warrant a judicial duel:
Another reason Talhoffer lists is of allies making insults to each other as a legally-warranted reason for trial by combat, although he names this practice as "wanton." Talhoffer's descriptions also implies that a peer could do his trial outside of the judicial arena, and fully describes the court processes.<1459 Fechtbuch>
The introduction of the Reichskammergericht in 1495 tilted the balance in favour of Roman law over regional legal traditions, and the practice of judicial duelling died out shortly thereafter.
When Henry II reformed English civil procedure in the Assize of Clarendon in 1166, trial by jury became available, and lawyers, guarding the safety of the lives and limbs of their clients, steered people away from the wager of battle. A number of legal fictions were devised to enable litigants to avail themselves of the jury even in the sort of actions that were traditionally tried by wager of battle. The practice of averting trial by combat led to the modern concept of attorneys representing litigants. In practice, a person facing trial by combat was assisted by a second, often referred to as a squire. The role of the squire was not only to attend the battle, but to arrange the particulars of the ceremony with the opposing squire. Over time, squires would meet and resolve the disputes during negotiations over combat.
Wager of battle remained in two forms of action dear to the honour-bound hearts of the aristocracy, however. The first was the writ of right, the most direct way at common law of challenging someone's right to a piece of real property. The second was the criminal appeal, a private criminal prosecution instituted by the accuser directly against the accused. It was not, like the contemporary appeal, a proceeding in a court of superior jurisdiction reviewing the proceedings of a lower court.
Such a private prosecution was last conducted in the case of Ashford v. Thornton in 1818, as recorded in The Newgate Calendar. Pronouncing judgement in favour of the accused's plea claiming the wager of battle, Justice Bayley of the King's Bench said that:
The accusation was quickly withdrawn after this judgement. Parliament abolished wager of battle the following year, in 1819, and at the same time they also abolished the writ of right and criminal appeals.
One of the last mass trials by combat, the Battle of the Clans, took place in Perth in 1396. This event took the form of a pitched battle between teams of around thirty men each, representing Clan Macpherson and Clan Davidson on the North Inch in front of the King, Robert III. The battle was intended to resolve a dispute over which clan was to hold the right flank in an upcoming battle of both clans (and several others) against Clan Cameron. The Clan Macpherson is thought to have won but only twelve men survived from the original sixty.
Trials by combat at common law in England were carried on with quarterstaffs, on a duelling ground of sixty feet square. Each litigant was allowed a rectangular, leathern shield, and could be armed with a suit of armour, provided that they were bare to the knees and elbows, and wore only red sandals on their feet. The litigants appeared in person; women, the elderly, the infirm of body, and minors could have champions named to fight in their stead. The combat was to begin before noon, and be concluded before sunset. Before fighting, each litigant had to swear an oath disclaiming the use of witchcraft for advantage in the combat, which oath is in words and figures as follows:
Either combatant could end the fight and lose his case by crying out the word "craven", from the Old French for "broken," which acknowledged "(I am) vanquished." The party who did so, however, whether litigant or champion, was punished with outlawry. Fighting continued until one party or the other was dead or disabled. The last man standing won his case.
The dispute was between members of the O'Connor clan (ie. sept) in King's county (modern County Offaly), who were persuaded by two judges (referred to in the account below) to bring the matter before the Irish privy council for resolution.
The dispute probably concerned dynastic power within the territory of the O'Connors, and the parties, Teig and Conor, had accused each other of treason; the privy council granted their wish for trial by combat, to take place on the following day, and for another such trial between two other members of the same sept, to take place on the Wednesday following.
The first combat took place as appointed, with the combatants "in their shirts with swords, targetts and skulles". An account of the proceedings as observed by one of the Privy Councillors is given in the State papers Ireland 63/104/69 (spelling adapted):
This was a trial not at common law but under consiliar jurisdiction. It can be seen as a neat example of classic divide-and-rule policy.
In late December, shortly after Christmas, the combatants met in the grounds of an abbey in the Northern Paris suburbs. After lengthy ceremony battle was joined and after a furious and bloody encounter, Carrouges stabbed his opponent through the throat with his dagger and claimed victory, being rewarded with substantial financial gifts and a position in the Royal household. The duel was watched by the Royal court, several royal dukes and thousands of ordinary Parisians and was recorded in several notable chronicles including Froissart's Chronicles and Grandes Chroniques de France. It has since been covered by several notable texts, including Diderot's Encyclopédie, Voltaire and the Encyclopedia Britannica Eleventh Edition.
At combat, Maquer was unable to contain the frenzied attack of the dog, who focused on Maquer’s throat. Maquer, undone by the dog’s fervor and tenacity, confessed to his crime and was duly hanged.