When determining the inventorship of a patent application, keep in mind that an inventor is anyone who significantly contributed to the conception of any claimed concept.
Conception exists when written evidence is available showing that an idea of a specific, complete, and operative implementation of the claimed concept was known first to the alleged inventor, provided that, using such evidence, a person having ordinary skill in the art corresponding to that claimed concept could have constructed and used that implementation without undue further research, experimentation, or training.
If that implementation was actually constructed, someone who only constructed that implementation and did not conceive it is not treated as an inventor. Likewise, to qualify as an inventor, one must do more than merely explain well-known concepts and/or the current state of the art. Further, one does not qualify as an inventor simply by supervising, managing, funding, or otherwise assisting an inventor. Instead, inventorship requires properly evidenced conception of a claimed concept.
Although not legally required, it can be a good idea to ask each potential inventor to identify at least one claim to which they made a material contribution, and to make sure the inventors agree (in writing) on those identifications. In other words, it’s usually better to resolve any inventorship concerns sooner rather than later.
Turning to ownership: in the US, each inventor owns the entirety of any patent claiming one or more of their claimed concepts (even if the patent fails to name them as an inventor!) and generally is permitted to financially exploit that patent as desired without accounting to any other inventor (if any). That means that when a patent has multiple co-inventors, absent any agreement to the contrary, if one co-inventor earns $1 million by exploiting (e.g., licensing out) a claimed concept, they legally owe nothing to their fellow co-inventors.
But often, an inventor is obligated to sell or transfer (i.e., “assign”) their rights in their innovative concepts to someone else. For example, a well-drafted Employment Agreement typically will automatically assign, from the employee to the company, at the moment of conception, each concept that was (1) conceived by the employee using company resources or (2) within the company’s field(s) of endeavor at that time. That Employment Agreement also will require the employee to sign (typically in the presence of a notary) a separate formal “Assignment Agreement” that confirms the assignment, obligates the employee to complete any other paperwork, and requires the employee take any further action that might needed in the future to secure the company’s ownership of each of that employee’s innovative concepts, including any patent application or patent that claims that concept and that names (or should name) that employee as an inventor.
Even in the absence of an Employment Agreement, sometimes, because the inventor conceived or implemented an innovative concept using their employer’s resources, the employer obtains at least limited “shop rights” to the concept, which will allow the employer to at least use the concept without accounting to the inventor.
Even when an inventor created and developed an innovative concept without any use of the employer’s resources, if the inventor was specifically “hired to invent”, the rights to the concept still might belong to the employer, particularly if it was within the scope of the employer’s current or planned business activities.
Periodic reviews of your company’s written agreements, including its Employment Agreements and Assignment Agreements, can provide answers to many questions concerning ownership. Sometimes an Agreement Audit can highlight opportunities to identify, clarify, and resolve existing ownership issues, and/or prevent them in the future.