Meaning: The words of deeds are to be taken most strongly against him who uses them.

This maxim is subject to the rule, that an instrument must be construed according to the intention of the parties, gathered from the whole instrument, and the maxim applies only where there is an ambiguity, requiring explanation, in the language of the instrument ; and where the construction to be put upon the language will not work an injury to third parties.

It applies to deeds, contracts, pleadings, and other written instruments, private statutes, etc, and may be exemplified as follows : A, being owner of the fee, grants to B an estate for life, without saying for whose life ; this shall be taken to be for the life of B, an estate for a man's own life being considered greater than an estate for the life of another.

Where A, being principal, contracts as agent, he will not be allowed to sue as principal without first divesting himself of the character of agent ; for, where a man assigns to himself the character of agent to another, whom he names, he will not be permitted at pleasure to shift his position and to declare himself the principal and the other a mere man of straw. As, where a man makes a purchase, pays a deposit, and agrees to comply with the conditions of sale as agent for another, and in the mere character of agent ; this agreement will be taken most strongly against him when he seeks to take the benefit of the contract for himself, as principal and not as agent ; to show that he was really treating in the character which he assigned to himself at the time of purchase ; so in all cases of contracts, in which the skill or solvency of the person named as principal may reasonably be considered as a material ingredient in the contract.

The governing principle under this maxim, in regard to contracts, as against the party making them, seems to be, that he who makes an instrument should take care so to express his own liability as not to bind himself beyond his intention, and that the party who receives an instrument shall have a construction put upon it in his favour, because the words of the instrument are not his but those of the other party. A distinction is suggested between an ordinary contract and a guarantee, the latter being, not a contract by the party for payment of his own debt, or on his own behalf, but for the debt and on behalf of a third person, and that in such case there is a duty on the party taking the guarantee to see that it is so expressed that the party giving it be not deceived.

The maxim must, however, be understood with this limitation, that no wrong be thereby done, for it is a rule, “ Quod legis constructs, non facit injuriam.” And therefore it is said, if tenant for life grants the land he so holds for life to another, without saying for what time, this must be taken for an estate for his own life, and not for that of the grantee, for otherwise there would be a forfeiture.

A distinction is also made between a deed poll and an indenture, the former being executed by the grantor alone, and the words used his only ; the latter by both parties, and the words the words of both. And further, that this rule, being one of rigour, is never to be resorted to but when all other rules of exposition fail.