Defenses etc. in Suits for Infringement :

(1) In any suit for infringement of a patent, every ground on which it may be revoked under Section 64 shall be available as a ground for defense.

(2) In any suit for infringement of a patent by the making, using or importation of any machine, apparatus or other article or by the using of any process or by the importation, use or distribution of any medicine or drug, it shall be a ground for defense that such making, using, importation or distribution is in accordance with any one or more of the conditions specified in Section 47. [Section 107]

In Cadila Pharmaceuticals Ltd. v. Instacare Laboratories Pvt. Ltd., 2001(21) PTC 472 (Guj), the Gujarat High Court observed that Section 107 expressly empowered a defendant to defend any suit for infringement of a patent. Every ground on which a patent could be revoked under Section 64 was available as a ground of defense. Though the defendant had chosen not to give notice of opposition under Section 25 of the Act or to apply for revocation under Section 64 of the Act, he still had the right to defend his action on any ground on which the patent could be revoked under Section 64 of the Act.