Insufficiency as a Ground of Revocation

1A patent may be revoked on the ground that the complete specification does not sufficiently and fairly describe the invention and the method by which it is to be performed. In other words, if the description of the method or the instructions for the working of the invention as contained in the complete specification are not by themselves sufficient to enable a person in India possessing average skill in, and average knowledge of, the art to which the invention relates, to work the invention, or it does not disclose the best method of performing it which was known to the applicant for the patent and for which he was entitled to claim protection, it may be a ground for revoking the patent.

2The language used in s 64(1)(h) is unique. The expression ’enables a person in India’ who is skilled in the art does not have any comparative provision in other laws. It represents the statutory recognition of the principles evolved by the court in determining sufficiency. (See Justice N Rajagopala Ayyangar, ‘Report on the Revision of the Patent Laws’, September 1959, para 576.)

3In J. Mitra v Kesar Medicaments (2008) the Delhi High Court, on an application for an interim injunction, held on a perusal of the complete specification that “The specification prima facie appears to have sufficiently explained the various components of the device and the impact of the said components/features.” (para 112)

4In Communication Components Antenna v Mobi Antenna Technologies (Shenzhen) (2022) the Delhi High Court held that “a party seeking revocation of a patent - must allege and show insufficiency of disclosure and specifically point out such deficiency and/or inadequacies in the patent specifications”, and that “With no evidence led on the grounds of insufficiency of disclosure, determination of the grounds of revocation would not be feasible for the Court, as pure a question of law. Such grounds for revocation cannot be determined plainly by reading the patent specifications.” (para 12) It held that “it cannot be said that insufficiency of a patent is purely a question of law that could be decided by the patent specifications” (para 13), and answered the issue for the patentee because “In the absence of such pleadings and no evidence having been led in this case, this Court cannot conclusively hold that IN240893 is insufficiently disclosed.” (para 14)

5In Communication Components Antenna v Rosenberger Hochfrequenztechnik (2026) the Delhi High Court, after trial, held that “On the aspect of insufficiency, the term ‘critical coverage area’ is clearly understandable from a reading of the suit patent” and that “The said term is not to be defined with mathematical precision but is to be broadly understood in the context of the invention.” (para 230) On the results claimed in the specification it held that “Until and unless, the Defendants prove that the result achieved at points (1) to (7) at pages 18 & 19 of the specification was either a mirage or mere imagination, the argument of insufficiency completely fails.” (para 262)

6Section 10 of the Patents Act requires the complete specification to satisfy certain conditions. It states that every specification, whether provisional or complete, shall describe the invention. It requires a complete specification to ‘fully and particularly describe the invention’, its operation or use and the method by which it is to be performed. It also requires the complete specification to disclose the best method of performing the invention which is known to the applicant and for which he is entitled to claim protection. The relevant provisions of s 10(4) of the Patents Act, which are similar to the requirements under s 64(1)(h), are detailed below:

10. Contents of specifications.—(1) Every specification, whether provisional or complete, shall describe the invention and shall begin with a title sufficiently indicating the subject-matter to which the invention relates. …
    (4) Every complete specification shall -

(a) fully and particularly describe the invention and its operation or use and the method by which it is to be performed; (b) disclose the best method of performing the invention which is known to the applicant and for which he is entitled to claim protection; and (c) end with a claim or claims defining the scope of the invention for which protection is claimed; …

(5) The claim or claims of a complete specification shall relate to a single invention, or to a group of inventions linked so as to form a single inventive concept, shall be clear and succinct and shall be fairly based on the matter disclosed in the specification.

7Where the complete specification mentions biological material, the applicant should satisfy the requirements mentioned in cll (a) and (b) of s 10(4).

8According to art 83 of EPC, the European patent application must disclose the invention in a manner sufficiently clear and complete for it to be carried out by a person skilled in the art. Section 72(1)(c) of UK Patents Act 1977 is similar in its ambit but does not make non-disclosure of the best method a ground for revocation. The earlier provision, ie s 32(1)(i) of the UK Patents Act 1949, was similar to s 64(1)(h) of the Patents Act.