MPEP 2161

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2161 Three Separate Requirements for Specification Under 35 U.S.C. 112, First Paragraph[edit | edit source]


The first paragraph of 35 U.S.C. 112 provides:

The specification shall 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, and shall set forth the best mode contemplated by the inventor of carrying out his invention. [emphasis added].

This section of the statute requires that the specification include the following:

(A) A written description of the invention;

(B) The manner and process of making and using the invention (the enablement requirement); and

(C) The best mode contemplated by the inventor of carrying out his invention.


The written description requirement is separate and distinct from the enablement requirement.

An invention may be described without the disclosure being enabling (e.g., a chemical compound for which there is no disclosed or apparent method of making), and a disclosure could be enabling without describing the invention (e.g., a specification describing a method of making and using a paint composition made of functionally defined ingredients within broad ranges would be enabling for formulations falling within the description but would not describe any specific formulation). See In re Armbruster, 512 F.2d 676, 677, 185 USPQ 152, 153 (CCPA 1975) (“[A] specification which ‘describes’ does not necessarily also ‘enable’ one skilled in the art to make or use the claimed invention.”). Best mode is a separate and distinct requirement from the enablement requirement. In re Newton, 414 F.2d 1400, 163 USPQ 34 (CCPA 1969).

2161.01 Computer Programming and 35U.S.C. 112, First Paragraph[edit | edit source]

The requirements for sufficient disclosure of inventions involving computer programming are the same as for all inventions sought to be patented. Namely, there must be an adequate written description, the original disclosure should be sufficiently enabling to allow one to make and use the invention as claimed, and there must be presentation of a best mode for carrying out the invention.

The following guidelines, while applicable to a wide range of arts, are intended to provide a guide for analyzing 35 U.S.C. 112, first paragraph, issues in applications involving computer programs, software, firmware, or block diagram cases wherein one or more of the “block diagram” elements are at least partially comprised of a computer software component. It should be recognized that sufficiency of disclosure issues in computer cases necessarily will require an inquiry into both the sufficiency of the disclosed hardware as well as the disclosed software due to the interrelationship and interdependence of computer hardware and software.


The function of the written description requirement is to ensure that the inventor had possession of, as of the filing date of the application relied on, the specific subject matter later claimed by him or her; how the specification accomplishes this is not material.


The purpose of the best mode requirement is to "restrain inventors from applying for patents while at the same time concealing from the public the preferred embodiments of their inventions which they have in fact conceived." Only evidence of concealment, "whether accidental or intentional," is considered in judging the adequacy of the disclosure for compliance with the best mode requirement. That evidence, in order to result in affirmance of a best mode rejection, must tend to show that the quality of an applicant's best mode disclosure is so poor as to effectively result in concealment.

There are two factual inquiries to be made in determining whether a specification satisfies the best mode requirement:

  1. there must be a subjective determination as to whether at the time the application was filed, the inventor knew of a best mode of practicing the invention.
  2. if the inventor had a best mode of practicing the invention in mind, there must be an objective determination as to whether that best mode was disclosed in sufficient detail to allow one skilled in the art to practice it.

"As a general rule, where software constitutes part of a best mode of carrying out an invention, description of such a best mode is satisfied by a disclosure of the functions of the software. This is because, normally, writing code for such software is within the skill of the art, not requiring undue experimentation, once its functions have been disclosed. . . . [F]low charts or source code listings are not a requirement for adequately disclosing the functions of software." Fonar Corp., 107 F.3d at 1549, 41 USPQ2d at 1805 (citations omitted).


When basing a rejection on the failure of the applicant's disclosure to meet the enablement provisions of the first paragraph of 35 U.S.C. 112, USPTO personnel must establish on the record a reasonable basis for questioning the adequacy of the disclosure to enable a person of ordinary skill in the art to make and use the claimed invention without resorting to undue experimentation.

Once USPTO personnel have advanced a reasonable basis for questioning the adequacy of the disclosure, it becomes incumbent on the applicant to rebut that challenge and factually demonstrate that his or her application disclosure is in fact sufficient.

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