I came across a fascinating little law called the "benefit of clergy" over at the Overcoming Bias blog. The basic idea of this wonderful law was that one could be tried in an ecclesiastical court as opposed to a secular court. The benefit, of course, of the ecclesiastical court was that one could seek a sentence of penance, as opposed to hanging.
I'm most intrigued by the political relationship between the king and the clergy:
Prior to the 12th century, traditional English law courts had been jointly presided over by a bishop and a local secular magistrate. In 1166, however, Henry II promulgated the Assize of Clarendon legislation that established a new system of courts that rendered decisions wholly by royal authority. The Assizes touched off a power struggle between the king and Thomas Becket, Archbishop of Canterbury. Becket asserted that these secular courts had no jurisdiction over clergymen because it was the privilege of clergy not to be accused or tried for crime except before an ecclesiastical court. After four of Henry's knights murdered Becket in 1170, public sentiment turned against the king and he was forced to make amends with the church. As part of the Compromise of Avranches, Henry was purged of any guilt in Becket's murder but he agreed that the secular courts, with few exceptions (high treason being one of them), had no jurisdiction over the clergy.
The best part about this was that you could show your clerical status by simply reading from the Bible:
At first, in order to plead the benefit of clergy, one had to appear before the court tonsured and otherwise wearing ecclesiastical dress. Over time, this proof of clergy-hood was replaced by a literacy test: defendants demonstrated their clerical status by reading from the Bible. This opened the door to literate lay defendants' also claiming the benefit of clergy. In 1351, under Edward III, this loophole was formalised in statute, and the benefit of clergy was officially extended to all who could read.