John Archibald Campbell

“ No authorities are needed to show, that, for an injury by an agent, the principal or the agent may be sued. The ownership of the infringing machine is immaterial; its use alone is in controversy; and it will be submitted, that such an use, by an agent, as is here proved, will render the principal liable.
3. Or, regarding the use as the result of a partnership, with the Maryland company, the defendants paying a proportion of losses and receiving a proportion of the profits, as such, from the use, the latter must be liable to the patentee. ”

“ But the case before us is, that the motive power on the road partly belongs to the plaintiff; that the agents and officers employed are in its service and are paid by it; and that the cars are fitted and repaired at the common expense of the two corporations. It follows, therefore, that the plaintiff is a principal, cooperating with another corporation, in the infliction of a wrong, and is directly responsible for the resulting damage. ”

“ The defendants were a Pennsylvania company, fully organized, and having possession of their road.
The uses made of their road, were their own uses. The road and the cars upon it are a single machine, the use of a part of which involves the use of all other parts. The cars are useless without the road. The road is useless without the cars. The terms upon which the cars are permitted to be used are immaterial. The injury complained of is the use. ”

“ If it were needful, it might be well contended that the relation of the companies was that of partnership. Corporations may form partnerships under circumstances, so far, at least, as to preclude them from setting up separate rights to the prejudice of third persons. ”

“ If they do make such a bargain, whether lawful or otherwise, and it result in a use by them of the patented improvement, the unlawfulness of the contract by which the use was accomplished can be no defence. ”

“ Young, in 10 Wheaton, 358. There Young was held not to be liable, because he only purchased the product of a machine; but it would have been different, had he taken the machine into his own keeping, and used it. ”