In Tudor times there was no organised police force. There were voluntary constables who would check that laws were kept and there were Cunning Men who acted as magical detectives. They would use spells and charms to weed out the guilty. They also claimed to be able to cure illness through the use of magic.
There were several methods for finding out who was guilty. Most worked on the basic principle of using chance. They would ask the suspects to perform a task similar drawing straws and the person with the shortest straw would be pronounced guilty. The logic behind it was based in religion, they believed that God would not allow an innocent man be punished without reason and so would select the man most worthy of punishment to be the guilty party.
To cure illness the Cunning Man would simply sell a “magic potion,” usually containing willow bark and various herbs, to the sick. More often than not they would get better of their own accord, but attribute it to the Cunning Man.
The Cunning Man might also tell fortunes, he would do this in much the same way as a newspaper horoscope does, by constructing a prediction vague enough that people’s own wishful thinking would make it appear to come true.
It is un-clear whether the Cunning Men actually believed themselves to be genuine, or whether they were true con-artists.