Under Section 84 of the Patents Act, 1970, after the expiry of how many years from the date of grant of a patent can any person apply to the Controller for a Compulsory Licence, and what are the grounds for such application?

Section 84(1) of the Patents Act, 1970 provides that at any time after 3 years from the date of grant of a patent, any person interested may apply to the Controller of Patents for grant of a compulsory licence on any of the following three grounds: (a) the reasonable requirements of the public with respect to the patented invention have not been satisfied; (b) the patented invention is not available to the public at a reasonably affordable price; or (c) the patented invention is not worked in the territory of India. India granted its first and only compulsory licence in the landmark case of Bayer Corporation v. Natco Pharma (2012), where the Controller granted Natco a compulsory licence to manufacture the anti-cancer drug Sorafenib Tosylate (Nexavar) on the grounds that it was not available at a reasonably affordable price and was not being worked in India. Before applying to the Controller, the applicant must demonstrate that they made reasonable efforts to obtain a voluntary licence from the patentee within 6 months, which were unsuccessful. Compulsory licensing is a key TRIPS-permitted flexibility to protect public health and access to medicines.