A common misconception is that inventorship is based on constructing or developing an operable product based on the conceived invention, also known as reduction to practice. While it is true that the invention is completed on reduction to practice, inventorship only requires conception. An invention may be reduced to practice in one of two ways: the invention can be actually reduced to practice by building a working invention, or the invention can be constructively reduced to practice by describing it well enough in a patent application such that a person of skill in that field can make it. Many people may be involved in the reduction to practice phase, as prototyping, testing, and manufacturing all fall within this phase of invention.
Where companies are often tripped up is determining inventorship through contributions at this stage. An engineer who builds a part to specification, follows the direction of a superior, or otherwise merely takes another’s conceived invention and puts it into real-life practice is not an inventor. Core to inventorship is the original idea; the manufacture of the invention is a secondary component. This means that the engineer who may have spent countless hours building and testing a product is not actually an inventor if they did not conceive of the invention to begin with.