He who does anything by another does it by himself ; or Qui per alium facit, per seipsum facere videtur : He who by another does anything is himself considered to have done it.
This maxim has reference to the law of principal and agent, and under it a principal is responsible for the acts of his agent ; as, where B. employs A. to buy goods for him, B. is liable in an action for the amount ; or to sell goods, A.'s receipt, though he subsequently misapply the money, will discharge the purchaser. Many nice distinctions arise in practice under this maxim, in applying it to the characters of principal and agent, and in considering the various rights and liabilities of principal and agent with reference to third parties ; and also in applying the character of principal and agent to the relation of master and servant, husband and wife, parent and child, attorney and client, bankers, auctioneers, partners, etc.
If a servant do what his master ought to, do, it is the same as though the master did it himself ; and if a servant do any such thing without the consent of the master, yet, if the master subsequently ratify the act of the servant, it is sufficient : “Omnis enim ratihabitio ratrotrahitur, et mandato aequiparatur.”
So the act of the agent is the act of the principal for everything done within the scope of his authority. The agent's receipt for money will charge his principal. His payment will discharge his principal. A tender to him of money or goods on sale, or a tender by him as agent for another, is good. So a tender of money to a clerk or servant having a general authority to receive money for his employers, is a good tender to the latter. A tender to an executor who has not then proved the will, if he afterwards prove, is a good tender to him as executor. And a tender of a debt to an attorney authorised to receive it, or to any one in his office on a day named, on a demand by him by letter, is a good tender to the creditor.
The contract of an agent will bind his principal in purchase or sale : payment to an auctioneer is payment to the vendor. The delivery of goods to a carrier's servant, or agent collecting goods for carriage by the carrier, is a delivery to the carrier. One railway company is the agent to bind another in carrying over various lines of railway of passengers or goods in one entire contract ; and so it has been frequently held.
The question in all cases of principal and agent, in which the plaintiff seeks to fix the defendant with liability upon a contract, express or implied, is stated to be, whether or not such contract was made by the defendant, by himself or his agent, with the plaintiff or his agent ; and this is a question of fact for the jury upon the evidence. The plaintiff, on whom the burden of proof lies in all these cases, must, in order to recover, show that the defendant contracted expressly or impliedly ; expressly, by making a contract with the plaintiff ; impliedly, by giving an order to him under such circumstances as show that it was not to be gratuitously executed ; and if the contract was not made by the defendant personally, then, that it was made by his agent properly authorised, and as his contract.
This maxim does not, however, apply to the acts of an agent of an agent ; in which case the maxim, “Delegatus non potest delegare” applies.