35 USC 102 (A) states that a person should be entitled to a patent unless “the claimed invention was patented, described in a printed publication, or in public use, on sale, or otherwise available to the public before the effective filing date of the claimed invention.” 35 USC 102(B) gives inventors 1 year from the disclosure date to file a patent application.
However, what exactly is “public use” in the eyes of the patent office. The leading case dealing with public use is Egbert v. Lippmann, 104 U.S. 333 (1881). In Egbert, the inventor gave an under-garment corset to his wife to wear. His wife wore the corset for a period of up to 11 years before a patent application was filed. However, there was no evidence that anyone saw the corset being worn because the corset was worn under her clothes. The Supreme court held that:
If an inventor, having made his device, gives or sells it to another, to be used by the donee or vendee, without limitation or restriction, or injunction of secrecy, and it is so used, such use is public, even though the use and knowledge of the use may be confined to one person.
Accordingly, the Supreme Court has held for many years that if an invention is disclosed to even 1 person, without minimizing the secrecy or disclosure of the invention, then that would mean public use. For this reason, when inventors are creating prototypes for their invention, they should list all materials as confidential and not for redistribution, etc. Therefore, at least there would be some written documentation about the confidentiality of the agreement.
Additionally, inventors should realize that being on “SHARK TANK,” forming a ‘KICKSTARTER” campaign, or even posting pictures of your invention on youtube, facebook, twitter, etc. can potentially bar the inventor from obtaining a patent on their invention.