Employees as well as employers are entitled to their own inventions and to patents granted therefor. This right can be modified by contract, but in the absence of a contract to the contrary an employee is entitled to a patent for any invention which he makes, even though it may relate to the business of his employer. If he develops the invention in the time, and at the expense and with the tools and material of his employer, then the latter will have an implied license or shop-right to use such invention in his business, but he cannot demand an assignment of the patent.

Employers who wish to secure inventions relating to their own business, which are made by others while in their employ, should have a contract with the employee. Even with such a contract the employer cannot apply for a patent in his own name, but the patent must be applied for by the employee and assigned to the employer.

Joint owners"of Patents. - Patents may be owned jointly by two or more parties, and these may have different fractional interests. A common misapprehension is that one joint owner of a patent may make, use or sell the patented invention without the consent of, and without accounting for profits to, his co-owners. This is an error. In the absence of a contract to the contrary, any co-owner of a patent, no matter what fractional interest he may hold, is free to assign his interest in the patent, or to manufacture, use and sell the patented device, or license others to do so, without the consent of his co-owners and without accounting for any part of the profits.

If, therefore, a person owns merely a one-hundredth share of the entire patent right, he may manufacture, sell or use the patented device without the consent of or accounting of the profits to, the owners of the other ninety-nine one-hundredths. By reason of superior facilities for manufacture or superior business ability, he may even monopolize the field so as to practically exclude his co-owners from deriving any income whatsoever from their share of the patent. He is nevertheless entirely within his right. The only way this can be prevented is by a properly drawn contract between the co-owners.