Chapter VI of the Patent Rules, 2003 deals with Opposition proceedings. Rule 55 states that opposition by representation against the grant of a patent be duly field via Form 7 and sent to the Controller in duplicate. Rule 57 lays down rule regarding filing of a written statement of opposition and evidence.
By the Patents (Amendment) Act, 2005 a dichotomy was inserted for the first time in the Patents Act with effect from January 1, 2005 by providing for “opposition to pre-grant” of Patent vide section 25(1) and for “opposition to post-grant” of patent vide section 25(2). By reason of the Patents (Amendment) Act, 2005, the kind of the opposition available under the Patents Act, 1970 is different from what existed earlier. Previously, there was no “post-grant opposition” and the only provision of challenge by an interested party was a “pre-grant” challenge under section 25(1) as it then stood. Therefore, the Courts evolved the “rule of caution” as the patent had not faced any challenge at the hands of interested parties. There is, however, a radical shift due to the incorporation of section 25(2) where an interested party is granted the right to challenge the patent after its grant.
The ground for challenge under section 25(1) is identical to section 25(2) of the Patents Act, 1970. Opposition to pre-grant of patent (section 25(1)) is wider than the opposition to post-grant of patent (section 25(2)) as the latter is available only to a “person aggrieved”. The main difference between sections 25(1) and 25(2), as brought by the Patents (Amendment) Act, 2005, is that even after a patent is granted, “post-grant opposition” can be filed for a period of up to 1 year.