It is said that the dependency may be expressed or implied, as the condition is expressed or implied, and that the doctrine of implied dependency was introduced by Lord Mansfield, in Kingston v. Preston, cited in 2 Dougl. 684, before which, if there was no expressed dependency, a breach by one party was no defence to an action by the other and only gave him a cross-action; Harr. Cont. 153.
What is meant by implied dependency may be stated : From the definition of depend ency it is clear that the term is used to de scribe certain conditions which necessarily belong only to bilateral contracts. As these conditions must originate in the intention of contracting parties, if expressed in the con tract, they are governed by the law of con ditions generally. In the absence of precise expression, the law imputes an intention, which creates an implied condition. The principles which regulate these conditions constitute the law of implied dependency and they are peculiar to the subject; Langd. Sum. Cont. 134.
The question of dependency is so much a matter of intention that there is much truth in the remark "that arbitrary rules are use less" ; Harr. Cont. 153. Nevertheless cer tain rules of construction have been general ly agreed upon and applied in the interpreta tion of contracts, with respect to this subject.
A note to Pordage v. Cole, 1 Wms. Saund. 319, termed by Pollock (Contracts 386) "the classic on the subject," gives the five rules of Mr. Serjeant Williams which are most referred to (Langd. Sel. Cas. Cont. 641, n. 5). These rules are adopted, in a different order, in Leake, Cont. 345, and substantially the same general principles have been grouped in four rules ; 1 Bouv. Inst. 701; Platt, Coy. 80. These classifications are extremely in teresting as affording a good illustration of what is practically an early codification of the principles governing an important branch of the law of contract, and, while the first is accessible, their repetition here is proper, as they must necessarily be referred to in con nection with the brief statement which pres ent limitations permit, of the rules of con struction generally accepted.
The rules of Mr. Serjeant Williams are: 1. If a
day be appointed for payment of money or part of it, or for doing any other act, and the day is to happen, or may happen, before the thing which is the consideration of the money or other act Is to be performed, an action may be brought for the money, or for not doing such other act before performance ; for It appears that the party relied upon .his rem edy, and did not intend to make the performance a condition precedent; and so it is where no time is fixed for performance of that which is the consid eration or the money or other act. 2. But when a day is appointed for the payment of money, etc., and the day is to happen after the thing which is the consideration of the money, etc., Is to be performed, no action can be maintained for the money, etc., before performance. 3. Where a covenant goes only to part of the consideration on both sides, and a breach of such covenant may be paid for in dam ages, It is an independent covenant, and an action may be maintained for a breach of the covenant on the part of the defendant without averring perform ance in the declaration. 4. But where the mutual covenants go to the whole consideration on both sides, they are mutual conditions, and performance must he averred. 5. Where two acts are to be done at the same time, as, where A covenants to convey an estate to B on such a day, and, in consideration thereof B covenants to A a sum of money on the same day, neither can maintain an action without showing performance of, or an offer to perform, his part, though it is not certain which of them is obliged to do the first act ; and this particularly applies to all classes of sale. 1 Wms. Saund. 320 b. The rules referred to as given by Bouvier (Inst. 701) are: When the mutual covenants go to the whole of the consideration on both sides, they are mutual conditions, the one precedent to the other. Where the act of one party must necessarily pre cede any act of the other, as where one agrees to manufacture an article from materials to be fur nished by the other, or to pay for goods on delivery, or to pay money on demand, the covenants are in dependent, and one act Is a condition precedent to the other.