Justice in 14th-century England was a bit of a joke. The system was plagued by inefficiency, corruption, superstition, and cronyism. But, assuming the investigators and court officials actually act in good faith, how did they determine guilt?

In many cases the verdict will depend entirely on the defendant's reputation, ie "is it in his character to commit such a crime?" It was very important in those days to be a man of good reputation. People are suspicious of outsiders and in many jurisdictions up to a third of all accused thieves and murderers are "vagrants".

Sometimes, a case may be settled through trial-by-combat. Either the accuser or the accused can demand that the matter be settled with a fight. Then, either they or their representatives will fight each other. If the accused wins, he is declared innocent.

Then there was torture. Medieval investigators did not appreciate that a torture victim will say anything to end the pain.