In the creation of the patent, you have two entities that are tied to it: the inventor and the assignee. Many times the patent inventor hands off the patent to a company as the assignee.
Pertaining to legality, who is allowed to sue for the patent infringement? The inventor, the assignee, or both of them?
In most cases the inventor (or assignor) assigns all of it's rights in the patent to the assignee. Thus, only the assignee has any rights in the patent. Accordingly, only the assignee can bring a suit for patent infringement.
For more information see the USPTO's Manual of Patent Examining Procedure, Ch. 300.
There are at least three possibilities:
If the assignment is partial (e.g. to a field, product or territory) or the license is partial, there may be more than one of the three capable of suing if the alleged infringement affects more than the assigned or licensed part. It is possible all 3 might join the suit as plaintiffs. And, the two or three can have separate attorneys to protect their separate interests, as a licensee might have a cause of action against a patent owner who failed to enforce a licensed patent and such failure materially damages the licensee. Often the license or assignment will, particularly if it is well drafted, contractually determine who has the right and/or duty to sue for infringement.
There might also be situations where a distributor or retailer, particularly an exclusive one, might have standing to sue if the Inventor, Assignee and Licensee chose not to take action against an infringer. In such a situation the distributor or retailer might also take action against the patent owner for failure to enforce the patent.
So, there might be different plaintiffs for different defendants. Choice of desired forum might have a bearing on who is chosen to sue. Patent litigation can get very complicated very quickly, and this is just about who sues who.
In the U.S., the Patent Act provides that a “patentee” is entitled to bring a civil action for infringement of his/her patent. This has been interpreted to cover the individual inventor(s) to whom the patent was issued as well as the inventor’s heirs or other successors in title. Alternatively, if the patentee conveys “all substantial rights” in the patent to a third party (such as an employer), the third party is treated as the patentee and has standing to sue in its own name.” This is the typical case where an assignee/employer sues on behalf of an inventor/employee. There is no “right to sue” for infringement separate from a conveyance of a proprietary interest in the patent.
Under the newly acted provisions of the AIA, since a non-inventor can now apply for a patent, I believe such a party would also have standing to sue for infringement, but I can’t say for certain off the top of my head.
So the party that “owns” a patent can commence an action for patent infringement, however, a licensee ordinarily cannot, unless the license exclusively grants “all substantial rights” in the patent (i.e. a license that is virtually equivalent to an assignment). In some circumstances, an exclusive license that grants something less than “all substantial rights” can permit the licensee to join the patentee in suing an infringer, but the licensee couldn’t bring suit on its own. A “bare licensee,” that is, someone who merely has non-exclusive permission to exercise one of the rights granted by a patent, doesn’t have standing to sue third parties for infringement, even if the patentee wants them too.
I disagree with the answer above to the extent it implies that a licensed distributor or retailer could bring a suit for patent infringement in the case that the patentee does not. They certainly might have a complaint against the patentee, depending on the terms of the license, but they would have no basis to sue the alleged infringer.
There are two cases -
In case of assignment, as answered by @Hal, the assignee can bring suit for patent infringement. Generally, when an inventor works for an employer, he/she assigns the patent to his/her employer, may not be so in all cases.
In the case of a license, depending upon the licensing agreement, either the licensor can bring suit, or the licensee, or in some cases both of them together can do that. This scenario is when a company/R&D unit/employer owns a patent and licenses it to another company/R&D unit.
Before the AIA became law, the inventors were presumed to own the rights to the patent. Now, after the AIA, the applicants are presumed to own the rights to the patent. Those presumption can be rebutted. An assignee is nothing more than a patent owner who has gained rights from the inventors. In the US, the right to sue for infringement requires that the plaintiff hold substantially all of the rights to the patent. So an exclusive licensee can usually sue without involving the patent owner, but other types of licensees are required to include the patent owner in the lawsuit as plaintiffs.
The given answers 1-3 all relate to the situation in the USA. In other jurisdictions it may differ. First of all in most other jurisdictions, the inventor will not automatically be the owner of the patent, but the applicant (who may be a natural but also a legal person) will be the owner of the patent. Thus, an inventor can be the owner, but in most cases will not be the owner of the patent. This owner may bring forward any charges to alleged infringers, the inventor (if not the owner) does not have such a right. Whether licensees are entitled to sue depends on the national law of the country where such a licensee would want to start a law suit and on the text of the license agreement. Thus, this can vary enormously from country to country.
