In the medieval legal system, the penalties imposed on clergy were far more lenient than those imposed on the rest of the population, because it was believed that clergy should not be subject to civil courts. They worked for God, so they were to be tried by an ecclesiastical court.
The principle was known, legally, as the "benefit of clergy," and it could mean the difference between life and death. In a secular court, the charges brought against you could mean the gallows. The same charges in an ecclesiastical court might mean a slap on the wrist.