The disclosure requirement lies at the heart and origin of patent law. A state or government grants an inventor, or the inventor's assignee, a monopoly for a given period of time in exchange for the inventor disclosing to the public how to make or practice his or her invention. If a patent fails to contain such information, then the bargain is violated, and the patent is unenforceable.
For instance, an insufficiency of disclosure might arise if references to standardisation documents are provided to support essential aspects of the invention, but if these references are not sufficiently precise so that "the skilled person would have to make ... undue efforts to find and get together the information it needs to carry out the invention".
Insufficiency is also a ground for revocation under Section 72 of the UK Patents Act.
In the "predictable arts", such as mechanical inventions and software inventions, very little description is required. A mere flow chart of a piece of software, for example, is adequate. Source code is not normally required. In the “unpredictable arts”, such as chemistry and pharmaceuticals, a very complete description is required.
In a recent U.S. court case, several of Jerome H. Lemelson patents covering bar code readers were held to be invalid because the specification was not complete enough for a person of ordinary skill in the art of electrical engineering to have made and used the claimed invention at the time the patent was filed (1954) without undue experimentation. In this case the court held that a person of ordinary skill in the art was a degreed electrical engineer with two years of experience as of the filing date of the original patent application, 1954. One of the challenges of this court case, which was decided in 2005, was to find experts on the state of the art who were alive in 1954.
In the United States, the sufficiency of disclosure requirement is complemented by an additional requirement, generally not found in other national patent jurisdictions: the "best mode requirement". According to the requirement, the disclosure must also contain the inventor's "best mode" of making or practicing the invention. For example, if an inventor knows that a liquid should be heated to 250 degrees for optimal performance, but discloses in the patent that the liquid should be heated to "above 200 degrees", then the inventor has not disclosed his "best mode" for carrying out the invention.
The "best mode requirement" only applies to what the inventor knows at the time the application was filed, not as to what was subsequently discovered.
United States patent law further requires, among other things, that the patent specification "contain a written description of the invention, and of the manner and process of making and using it, in such full, clear, concise, and exact terms as to enable any person skilled in the art to which it pertains, or with which it is most nearly connected, to make and use the same." 35 U.S.C. 112(1). The requirement "to enable" a person of ordinary skill in the art to make and use the invention is colloquially referred to as the "enablement" requirement. A patent that does not meet the enablement requirement may be declared invalid by a court.