Medieval law is a tricky thing to nail down, since obviously different countries, regions, and ethnic groups/tribes had very different laws that each group of society adhered to. Since Medieval times covers several centuries, that also obviously affects the laws and customs one would have been subject to. The Norse often times had a very simple solution to a conflict: trial by combat. If a heinous crime was committed, and everyone knew beyond a shadow of a doubt who it was, then that individual would be hunted, but assuming that there were charges, a common response would be for the one leveling the charges, and the one being charged, to go an abandoned island, each with a weapon. Whoever won the fight took the boat home and was viewed as the destined (and therefore justified) winner.
The Germanic tribes that conquered the Roman Empire in the 5th century carried their own procedure with them into the conquered territories. Their procedure was surprisingly formal: in court, which was a gathering of all the freeborn men, the parties had to formulate their allegations in precise, traditional language. The use of even a few improper words could mean losing. At this point the court determined what method of proof should be used: ordeal, judicial combat between the parties, or wager of law (which means each side had to attempt to obtain more persons who were willing to swear on their oaths as to the uprightness of the party they were supporting).
Roman law procedure, even after the fall of the Roman Empire, never entirely disappeared from the territories conquered by the Germanic tribes. Eventually a modified form of Roman law was used in most of Europe, and even Germany itself, with the notable exception of Scandinavia which kept its local customs.
The Roman-canonical procedure, with its heavy reliance on written, rather than oral, presentations, created the need for learned counsel, or the beginning of lawyers. The whole procedure was divided into rigidly formalized stages. Precise rules governed the presentation of evidence but the concordant testimony of two male witnesses amounted to “full proof,” and one witness was ordinarily insufficient to prove any matter, unless he was a high ecclesiastic. There were many other complex procedures, but this was not efficient for businesses, which resulted in almost a side court for specific business arbitrations to spring up to bring order, without harming, mercantile centers.
Of course, to many a person’s misfortune, the rule of mob still applied. This was especially true during an inquisition, or anytime a woman was put on trial as a witch. An armed mob was always capable of taking the law into their own hands, and often did, which was a sad irony, considering the “barbaric” law system of the Norse actually helped to prevent that type of thing from happening.