This section is from the book "The Law Of Contracts", by William Herbert Page. Also available from Amazon: Commercial Contracts: A Practical Guide to Deals, Contracts, Agreements and Promises.
The ecclesiastical courts were ready to enforce contracts in order to prevent the promisor from committing a sin by breaking his contract, especially where he had pledged his faith.1 While it is often said that the fifteenth article of the Constitution of Clarendon withdrew all contract cases from the ecclesiastical courts, the article itself has no such broad provision; but it merely provides that debts which are due either with or without a pledge of faith are to be within the jurisdiction of the king. From its terms this applies only to debt and has no application to other classes of contract. Very likely it was put in this form because debt was at that time the contract which the king's courts recognized and enforced. At the same time this article was intended to protect the courts of the king from encroachment upon their jurisdiction by the ecclesiastical courts and it was not intended to limit the jurisdiction of the ecclesiastical courts in cases in which the king's courts would not grant relief. The operation of this article was not as complete or extensive as its terms would import. It is plain from the actual practice of the courts that the ecclesiastical courts took the position that they had the right to continue to hear cases of this sort, although they were obliged to concede that the debtor could prevent them from exercising their jurisdiction by securing a prohibition from the king's courts. If such prohibition were secured, the ecclesiastical courts could not proceed with the case. If the prohibition were not secured, they felt that they had jurisdiction to hear and determine actions of debt, at least if a pledge of faith had been given. The two sets of courts were regarded as having inconsistent rights; the ecclesiastical courts to hear the cases unless the king's courts issued a prohibition; the king's courts, to issue a prohibition to prevent the ecclesiastical courts from hearing the cases.2 It was much like the relation which exists to this day in some classes of cases between the common law courts and equity courts, where the plaintiff has a right to maintain an action at common law, to enforce his legal rights, even if he will thus obtain an inequitable advantage, although the equity courts may enjoin him from making use of his legal rights. The difference between the two was the rather technical difference that the prohibition issued to the ecclesiastical court, as well as to the plaintiff therein, while equity never assumed to issue an injunction against the king's courts, but only against the parties who sought relief therein.
For specific customs of different boroughs, see 18 Selden Society (I Borough Customs), 213, 215.
For cases in which contracts, apparently executory and informal, were enforced by local courts, see 4 Selden Society (The Court Baron), 114, 115.
1 For the attempt of the courts Christian to enforce the pledge of faith, see I Pollock & Maitland (2d Ed.), 128, 129; III Holdsworth, History of English Law, 318 et seq.
For a discussion of the relations between the ecclesiastical court? and the common law courts, see Breach of Promise of Marriage, by J. Dundas White, 10 Law Quarterly Review, 135 (1894). See The Date of Separation of Ecclesiastical and Lay Jurisdiction in England, by Walter Lichtenstein, 8 Illinois Law Review, 347.