Shall We Amend the Claims During Litigation?- AGC Flat Glass Europe Sa vs Anand Mahajan And Ors

First Publication Date: 9th November 2009
In my earlier post I had discussed about the prosecution and litigation and the effects of prosecution on the outcome of litigation.
Friends, here is a case where the Delhi High Court has allowed a Patent holder to amend his claim (or, should I say extending the scope of claim) after a suit for infringement has been filed.
An Indian Patent (no. 190380) has been granted to AGC flat glass (formerly, known as Glaverbel). AGC files a suit for infringement against Saint Gobain Glass (alleged infringer).


1) AGC’s invention is a product called Mirox New Generation Ecological Mirrors (hereinafter referred to as MNGE), which is a mirror without a copper or lead layer, is obtained through an environmentally friendly process and is available at the traditional selling price.
2) AGC wants to amend claim 1 based on the prior art cited by SGG. The amendment is by way of introducing “a sensitizing material, typically tin” in clause ii of claim 1 (reproduced below).
3) The above amendment has been sought allegedly after 12 years of the patent grant.


Whether the amendment sought by AGC is in compliance with sections 58 and 59 of the Indian Patent Act 1970 (reproduced below) and, whether the amendment can be allowed, entered and considered for further proceedings.

Analysis by the Court:

In deciding whether the amendment should be allowed, the court considered an entirety of the specification of the registered patent, which discloses that the invention works on 3 steps, viz, a) sensitizing process; b) Activating process; and c) Silvering process and claim 9.


The amendment was allowed.

Given the above backdrop, it is apparent that AGC intended to broaden the scope of claim 1 by adding the feature “a sensitizing material, typically tin” into clause (ii) of claim 1 which is a Markush type. The court mentioned that the amendment of claim 1 is a narrowing amendment which I respectfully disagree since the amendment sought increases the number and/or option of elements inside a group and thereby broadens the scope of the claim.
Prima facie, do these types of amendment, altering the scope of the claim during litigation, justify the existence of something called as “prosecution stage”, where the Applicant and the Examiner spend considerable time together for defining and finalizing the boundary of the invention, for the patent application?
Shouldn’t there be a provision where the above mentioned type of issues can be handled efficiently? For example, in the US whenever any patent is, through error without any deceptive intention, deemed wholly or partly inoperative or invalid by reason of the patentee claiming more or less than he had a right to claim in the patent; the applicant may file for a Reissue (35 U.S.C §251). During the reissue, the application is once again examined and if it is deemed that the amendment is necessary to overcome the identified issue a reissue patent is granted. Further, if the applicant wishes to broaden the claim, then he/she has to file for reissue within 2 years of patent grant. In the present case, the amendment has been sought allegedly after 12 years of patent grant!!
Further, allowing these types of amendments during the litigation stage/at a stage where substantial amount of the patent term is completed, tend to encourage applicants to prosecute the application only for the sake of getting a grant. The reason being that the Applicant at a later stage will be allowed, (i) based upon his need and (ii) based upon the type of the product which is manufactured by his/her competitor, to introduce features hidden inside the specification into the claims. That is to say that initially the claims of a patent being granted by the patent office will be unduly narrower and out of the blue, during litigation the patentee broadens the claim, thereby misguiding the public regarding the scope of the invention throughout the term of the patent.
If the Amendment of this sort is allowed during litigation, then it appears that the patent application need not go through the prosecution stage but simply be granted as it was filed.
There are certain concerns in the way the claim has been drafted which I will try to cover in my future posts.

Claim 1

“1) A Mirror with no copper layer comprising:
i) a vitreous substance,
ii) at least one material selected from the group consisting of bismuth, chromium, gold, indium, nickel, palladium, platinum, rhodium, ruthenium, titanium, vanadium and zinc at the surface of the said substrate,
iii) a silver coating layer on the surface of the said substrate, said silver layer optionally comprising at least one material selected from the group consisting of tin, chromium, vanadium, titanium, iron, indium, copper, and aluminum present at the surface of the silver coating layer and/or traces of silane; and
iv) at least one paint layer covering said silver coating layer.

Sections 58 and 59 Section 58 :

(1) In any proceeding before the High Court for the revocation of a patent, the High Court may, subject to the provisions contained in section 59, allow the patentee to amend his complete specification in such manner and subject to such terms as to costs, advertisement or otherwise, as the High Court may think fit, and if in any proceedings for revocation the High Court decides that the patent is invalid, it may allow the specification to be amended under this section instead of revoking the patent……

Section 59 :

(1) No amendment of an application for a patent or a complete specification shall be made except by way of disclaimer, correction or explanation, and no amendment thereof shall be allowed, except for the purpose of correcting an obvious mistake, and no amendment of a complete specification shall be allowed the effect of which would be that the specification as amended would claim or describe matter not in substance disclosed in the specification before the amendment, or that any claim of the specification as amended would not fall wholly within the scope of a claim of the specification before the amendment……..
(2) (c) the right of the applicant or patentee to make amendment shall not be called in question except on the ground of fraud.
Image Source/Attribution here  (Governed by Creative Commons License CC BY – SA 3.0)


  • November 10, 2009 Posted
    Dr. Kalyan

    Som, I think the Court’s analysis from a literal interpretation of sections 58 and 59 is right. The sections no where state that only narrowing amendments must be allowed. Section 59 states that an amendment can be in the form of an explanation or disclaimer, which means broadening of claims is also possible. The court’s role while deciding on an amendment is only to verify if the amendment falls within the scope of the specification and if it does it can permit the amendment. The Court has gotten that right in this instance.

    Having said that, I disagree with the judge with respect to the stage at which an amendment is allowed. As per Section 58, the Court can permit a patent holder to amend the specification in order to over come revocation. According to me, such an amendment has to be allowed by the Court after a decision on revocation is made and the patent will be susceptible to revocation unless an amendment is made. If making an amendment allows the patent holder to circumvent the revocation such an amendment may be allowed. I think allowing amendments at the stage of a plea for revocation as done by the Court is not in consonance with what the section states.

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