'There are two kinds of opposition in grant of patent.' Discuss the provisions of Pre grant opposition and procedure followed in such situation as per the Patent legislation.

There are two types of opposition to the grant of a patent as per Patent Amendment Act, 2005. They are: Pre-Grant Opposition Post-Grant Opposition. Pre-Grant Opposition Section 25 of the Act deals with opposition to the grant of a patent and provides that where an application for a patent has been published but a patent has not been granted, any person may, in writing, represent by way of opposition to the Controller against the grant of patent on the following grounds and the Controller on request of such person shall hear him and dispose of the representation in the prescribed manner and specified time. The grounds of the Pre-Grant opposition are as follows: That the applicant for the patent or the person under or through whom he claims, wrongfully obtained the invention or any part thereof from him or from a person under or through whom he claims; That the invention so far as claimed in any claim of the complete specification has been published before the priority date of the claim - In any specification filed in pursuance of an application for a patent made in India on or after the 1st day of January, 1912; or In India or elsewhere, in any other document: Provided that the ground specified in sub-clause (ii) shall not be available where such publication does not constitute an anticipation of the invention by virtue of sub-section (2) or sub-section (3) of section 29; That the invention so far as claimed in any claim of the complete specification is claimed in a claim of a complete specification published on or after the priority date of the applicant's claim and filed in pursuance of an application for a patent in India, being a claim of which the priority date is earlier than that of the applicant's claim; That the invention so far as claimed in any claim of the complete specification was publicly known or publicly used in India before the priority date of that claim. Explanation—For the purposes of this clause, an invention relating to a process for which a patent is claimed shall be deemed to have been publicly known or publicly used in India before the priority date of the claim if a product made by that process had already been imported into India before that date except where such importation has been for the purpose of reasonable trial or experiment only; That the invention so far as claimed in any claim of the complete specification is obvious and clearly does not involve any inventive step, having regard to the matter published as mentioned in clause (b) or having regard to what was used in India before the priority date of the applicant's claim; That the subject of any claim of the complete specification is not an invention within the meaning of this Act, or is not patentable under this Act; That the complete specification does not sufficiently and clearly describe the invention or the method by which it is to be performed; That the applicant has failed to disclose to the Controller the information required by section 8 or has furnished the information which in any material particular was false to his knowledge; That in the case of convention application, the application was not made within twelve months from the date of the first application for protection for the invention made in a convention country by the applicant or a person from whom he derives title; That the complete specification does not disclose or wrongly mentions the source of geographical origin of biological material used for the invention; That the invention so far as claimed in any claim of the complete specification is anticipated having regard to the knowledge, oral or otherwise, available within any local or indigenous community in India or elsewhere. The grounds for both pre and post-grant opposition are identical and there is nothing to preclude a pre-grant opponent from subsequently filing a post-grant opposition. However, despite the similarities, there are also several procedural differences between the two types of opposition. The primary difference between pre-grant and post-grant opposition is that though pre-grant proceedings may be initiated by "any person", but only a "person interested" can institute a post-grant opposition. The Indian Patents Act defines a "person interested" as including a person engaged in, or in promoting, research in the same field as that to which the invention relates. Moreover, the Indian Patents Act does not explicitly allow the opponent to be heard in a pre-grant opposition. The opponent has to make a request for hearing and the rules do not detail how a hearing is to be conducted. The opponent's right to be heard solely depends upon the discretion of the Controller, who decides the same based upon the merit of the opposition. Additionally, the rules are also not clear whether the opponent will be heard in the presence of the applicant. Opposition Proceedings Rule 55 dealing with opposition by representation against the grant of patent requires the representation for opposition under section 25(1) to be filed at the appropriate office within a period not exceeding three months from the date of publication of the application under section 11A of the Act, or before the grant of patent, whichever is later and includes a statement and evidence, if any, in support of the representation and a request for hearing if so desired. The Controller has been empowered to consider such representation only when a request for examination of the application has been filed. On consideration of the representation if the Controller is of the opinion that application for patent shall be refused or the complete specification requires amendment, he shall give a notice to the applicant to that effect. On receiving the notice the applicant shall, if he so desires, file his statement and evidence, if any in support of his application within one month from the date of the notice. On consideration of the statement and evidence filed by the applicant, the Controller may either refuse to grant a patent on the application or require the complete specification to be amended to his satisfaction before the patent is granted. After considering the representation and submission made during the hearing if so requested, the Controller shall proceed further simultaneously either rejecting the representation and granting the patent or accepting the representation and refusing the grant of patent on that application, ordinarily within one month from the completion of above proceedings. In the case of Novartis Agv. Natco Pharma Ltd. on 25 January, 2006, an application for patent was filed in India on 17th July, 1998 by Novartis AG, Switzerland, claiming Switzerland priority date of 18th July, 1997. Upon publication, the grant of patent was opposed by Natco Pharma Ltd., India on 26th May, 2005. The grounds for opposition were: Anticipation by prior publication Lack of inventive step Non-patentability under section 3(d) Wrongfully claiming the priority The title compound was already known in a US patent (filed in 1993). The US patent claimed a pharmaceutically acceptable salt of the base compound. Another Document, "Nature Medicine" (5th May, 1996) also described the title compound. Also, the claimed salt inherently existed in the most stable form of the salt. Hence, the claims of the application for the product and process in respect of the title compound stood anticipated by prior publications. Additionally, based on section 3(d) the product claim amounted to a mere discovery of the new form of the known substance. Further, the application had claimed Swiss priority, but Switzerland was not a convention country on the date of filing in Switzerland. Hence, no priority of Swiss application could be claimed in respect of the Indian application. In view of the above findings and arguments the Controller ruled that the above patent application cannot proceed for grant of patent.