Breakin' the Law
Example of Multiple Jurisdictions
The Vehmic Courts of Westphalia
This isn't an especially important or well-known example, but it's illustrative. They were a set of local courts in northwestern Germany that for a while had a much wider authority.
The Vehmic courts developed as strictly local baronial courts, much the same as countless others. They did not meet regularly but were always ad hoc, meeting to hear a particular case. In the beginning, they were convened in order to hear cases that manorial courts couldn't handle. They weren't quite a court of appeals, but they did in fact wind up hearing cases that had already appeared in some other court.
Membership on the court was prestigious, and locals paid for the right to be a member of the court. There was a practical advantage, not only because the members received a percentage of the fines levied, but also because they could exert some influence over local disputes. The status of the courts was raised by the Luxembourg emperors in early 14th century so that they could regularly be a court of appeal.
They began hearing appeals on capital crimes in the 14th century, and later in the century began receiving appeals from places outside Westphalia. If the trial were capital, the judges were sworn as wissend, a word that nominally means "wide man" but has overtones of secrecy. Membership included a secret ceremony and password. The trials were closed, to protect the identity of the wissend, because the sentence was nearly always execution, or else exile. In any case, there was always concern over retribution from the family of the condemned.
The atmosphere of the courts lent itself to rumor. After all, they met in secret, the accused was never present, they issued their decree, and the condemned was executed. Sometimes this entailed armed men knocking on the fellow's door in the middle of the night, dragging him out and killing him on the spot.
The Vehmic courts reached their heyday in 1430s and 1440s, when they were hearing cases from as far away as Switzerland. Eventually they overreached themselves, condemning great lords or entire cities, issuing sentences that could never be carried out. By late 1400s they were strictly controlled, but by that time their reputation had passed into legend with their secret judges and trials.
A later court in England had something of the same legend—the Court of the Star Chamber. The Vehmic courts were never as powerful, for they were not backed by royal power, nor were they as sinister as the later stories would have us believe. The courts were, however, a good indication of how organic, how ad hoc, was medieval justice. Without strong central authority, justice was administered in a bewildering variety that shifted with every generation.