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57 
form them of the customs of the merchants and converting 
the custom of merchants into a custom of decision in mercan- 
tile causes, and after once determined a precedent to be fol- 
lowed as much as any other judicial precedent. The chief 
contributions of the law merchant to our law are the law of 
negotiable instruments and the law of insurance. But in mod- 
ern times merchants have contributed a number of principles 
to the law of bills of lading and warehouse receipts, thru usage 
and scientific discussion. 
4. Canon Law. The canon law is that body of law admin- 
istered by the church in the Middle Ages. It was largely de- 
rived from the Roman law. It was to a considerable extent 
incorporated into the law of equity both in the matter of sub- 
stantive law and legal procedure, because of the fact that most 
of the early chancellors were ecclesiastics. It also contributed 
most of our law of probate and divorce, since the Ecclesiastical 
Courts in England retained this jurisdiction until most of its 
principles were settled. The mode of proof — examination of 
adversary under oath and examination of witnesses before trial 
— which canon law contributed to equity, was not derived from 
Roman law but developed by itself. 
C. Books of Authority. In Anglo-American law, contrary 
to the fact in other systems of law, there are few books of 
authority. Littleton’s treatise on tenures and Coke’s state- 
ment of the common law of the classical period in which he 
lived, which is found in his Commentaries on Littleton , are 
authorities upon the subjects on which they treat as to the 
law of those times. The books of Glanvil, Fleta, Br acton, and 
Sir Mathew Hale are also sometimes spoken of as authority, 
and Blackstone’s Commentaries and Kent’s Commentaries. 
