Under U.S. patent law, premature public use or sale of an invention constitutes a statutory bar to patentability unless the use or sale was carried on as a bona fide experiment [35 U.S.C. 102(b)]. An experimental use or sale is a use or sale with the motive of actually testing and/or perfecting the invention.
The intent of the inventor is an important consideration in determining whether a public use or sale meets the experimental exception. In that a variety of factors must be taken into account to establish "intent," such a determination is not always straightforward or simple. Among the factors that must be considered are whether a document was prepared at the time of the event that states that the use was experimental and describes the conditions under which and term during which the invention was made accessible to the other party, whether a signed confidentiality agreement was obtained from the other party, whether the inventor took an active part in controlling the tests and/or evaluating the data produced by the activity, and whether and when the invention was actually reduced to practice. In the light of fact that there is no recourse from a statutory bar and the reality that experimentation often occurs in the development of an invention, the prudent inventor takes appropriate precautions before embarking on such a course of action and maintains evidence that those precautions were followed.