Claims: Function and Form

1The chief function of the claim is to define the scope of the invention for which protection is claimed. The claim is that part of the specification primarily designed for delimitation. (British United Shoe Machinery Co Ltd v A Fussell & Sons Ltd (1908) 25 RPC 631, p 650 cited in AssiDoman Multipack Limited v The Mead Corpn (1995) RPC 321, p 328.) In other words, the claim limits the monopoly of the patent. (Patents Act 1970, s 10(4)(c).) The function of the claims has been best-described by Lord Russell of Killowen in Electric & Musical Industries v Lissen Ltd as following:

The function of the claims is to define clearly and with precision the monopoly claimed, so that others may know the exact boundaries of the area within which they will be trespassers. Their primary object is to limit, and not to extend, the monopoly. What is not claimed is disclaimed. The claims must undoubtedly be read as part of the entire document, and not as a separate document. Nevertheless, the forbidden field must be found in the language of the claims, and not elsewhere. (Electric & Musical Industries v Lissen Ltd [1938] 4 All ER 221, p 224, (1939) 56 RPC 23, p 39 cited in Kirin-Amgen Inc v Hoechst Marion Roussel Ltd [2005] 1 All ER 667.)

2In Syngenta v Controller of Patents and Designs (Delhi, 13 October 2023) the Division Bench said, “We also agree with the submission of learned counsel appearing for the intervener when he contended that the precept of ‘what is not claimed is disclaimed’ has no application to drafting of claims.” (para 29) It held that “while the aforesaid doctrine may be relevant for infringement analysis, it has no application to the subject of divisional filing and claim drafting. There thus does not appear to be any justification to impute the principle of ‘what is not claimed is disclaimed’ for the purposes of discerning the scope of Section 16.” (para 30)

3In Imperial Chemical Industries v Controller General of Patents, Designs and Trade Mark (1977) the Calcutta High Court, listing the propositions it took to be well-settled, held that “In order to have a complete patent, the specifications and the claims must be clearly and distinctly mentioned” and that “It is the claims, and claims alone which constitute the patent.” (para 12) It came to that conclusion from the English and Australian material it had reproduced, and in particular from the words of Lord Russell of Killowen in E. M. I. Limited v Lissen Ltd, the judgment quoted at para 1 above, which it recited, “A claim is a portion of the specification which fulfils a separate and distinct function. It, and it alone, defines the monopoly; and the patentee is under a statutory obligation to state in the claims clearly and distinctly what is the invention which he desires to protect.” (para 11, adopted at para 12)

Role of working examples

4In Bayer Pharm Aktiengesellschaft v Controller General of Patents and Designs (2024) the Delhi High Court held that “the claims of a patent define the boundaries of the patent protection”, that “they set out the legal limits of what the patent covers”, and that “Working examples, on the other hand, are provided in the subject application to demonstrate the practical implementation of the invention”, so that “while working examples are essential for demonstrating the feasibility and workability of an invention, they do not define the patent’s scope. The scope is determined by the claims, which must be interpreted in light of the description and any examples provided.” (para 9) Following that judgment, the same Court held in Array Biopharma v Deputy Controller of Patents and Designs (2026) that “It is trite that working examples are provided by the patentee to demonstrate the workability and practical implementation of the claimed invention”, and that “Thus the mere providing of examples does not describe the scope of the patent.” (para 50)

5Every complete specification should end with a claim or claims. As a matter of practice the specification will include many claims some of which are broad and general, and others which are more specific. The object achieved in having many claims is that some of them may be upheld even if others are struck down. As the Patents Act limits an application to a single invention, the claims too shall relate to a single invention. The claim may also relate to a group of inventions which are so linked together to form a single inventive concept. (Patents Act 1970, s 10(5).) The claims shall be clear and succinct, and shall be fairly based on the matter disclosed in the specification. In fact, a patent may be revoked if the scope of any claim of the complete specification is not sufficiently and clearly defined or if any claim of the complete specification is not fairly based on the matter disclosed in the specification. (Ibid, s 64(1)(i).) The Controller has the power to exclude irrelevant matters from the claims. (Patents Rules 2003, r 13(5).) The complete specification may include further claims in respect of developments and additions made to the invention which did not form part of the provisional specification.

6The object of the claim is to limit, and not widen the monopoly. The claims should clearly and precisely define the boundaries or limits of the monopoly claimed in the invention so that research and development of the area excluded by the patent is not hampered. An applicant should ‘mark out with adequate distinctness the boundary of the territory that he claims to be exclusively his own’. (Clay v Allcock and Co Ltd (1906) 23 RPC 745 (CA) cited in Ram Narain Kher v Ambassador Industries (1975) AIR 1976 Del 87, p 88.) The Delhi High Court there stated the proposition in its own words, “The function of the claim is ’to define the scope of the invention claimed’. Claim must be clear. The applicant must describe the advantage sought to be achieved by his invention in the claim.” (para 8) Of the claim before it the Court said that “the Plaintiff has not stated the advantage sought to be achieved by his invention; in other words ’the boundary of the territory that he claims to be exclusively of his own.’” (para 14)

7In ITC v Philip Morris Products (2026) the Delhi High Court found “merit in Patentee’s argument that where a structural element is associated with a functional element, the latter limits the claim to structures that are capable of performing that function”, and applied it to the claim before it, where “the structural aspect is the wrapper with its feature of being thermally-conductive and it limits the scope of Claim 1 by its functionality of acting as a flame barrier.” (para 70) Because “the novelty resides in limiting the claim such that there is no ignition/combustion in the aerosol-generating substrate when flame is applied to the aerosol-generating article”, the Court held that “therefore, the functional element serves as a screening assay.” (para 74)