Answer ... A patent becomes unenforceable if:

• the term of the patent expires (Section 53 of the Patents Act, 1970);
• the patent is surrendered in the prescribed format (Section 63); or
• the patent is revoked (Sections 64, 65 and 66).

If the patent has ceased to have effect due to non-payment of the renewal fee, it will become unenforceable between the date on which it ceased to have effect and the date of publication of the application for restoration of the patent (Section 62(2)).

Revocation of a patent can occur when an interested person or the central government petitions the high court for revocation. Revocation can further be sought by way of a counterclaim in a patent infringement suit before a high court. A patent can also be revoked by a high court, on the petition of the central government, if the court finds that the patent owner has, without reasonable cause, failed to comply with a request of the central government to make, use or exercise the patented invention for the purposes of government within the meaning of Section 99, upon reasonable terms. Revocation of a patent is statutorily possible if the invention relates to atomic energy under Section 65; and in certain cases a patent may be revoked by the central government in the public interest under Section 66.

Answer ... The doctrine of inequitable conduct standards has not been strictly recognised by the Indian courts. The Patents Act, 1970 provides for revocation of a patent when information is not disclosed by the patent owner during prosecution of the patent application or when false information is furnished.

In addition, non-disclosure of information regarding foreign applications is also considered inequitable conduct that can lead to revocation of the patent, under Section 64(1)(m) read with Section 8.

In Maj (Retd) Sukesh Behl v Koninklijke Phillips Electronics FAO (OS) No 16 of 2014 (2014 SCC OnLine Del 2313), the Delhi High Court, interpreting Section 64(1)(m) read with Section 8, held that the non-disclosure of information or the false representation alleged to be made by the patent owner must be deliberate and intentional to lead to revocation of the patent.

Answer ... The duty of candour is statutorily enshrined in Section 8 of the Patents Act, 1970. Section 8 mandates that a patent application be accompanied by a disclosure of information and undertaking regarding foreign applications which may have been filed by the applicant either alone or jointly or where, to its knowledge, such an application is being prosecuted by some other person.

The applicant must provide a statement with detailed particulars of such applications and also an undertaking that until the patent is granted, it will keep the Controller General of Patents, Designs and Trademarks informed from time to time of detailed particulars in respect of any other application relating to the same or substantially the same invention filed in any country outside India subsequent to filing of the aforementioned statement.

In Chemtura Corporation v Union of India (2009 SCC Online Del 2634) the court held that as far as Section 8(2) is concerned, the controller may also require the applicant to furnish details relating to the processing of the application in a country outside India, in which case the applicant shall furnish to the controller all information available to it within such period as may be prescribed. This requirement is mandatory, as is further emphasised by the wording of Section 64(1)(j) (which concerns an applicant’s failure to disclose to the controller the information required by Section 8 or provision of information which in any manner was false to its knowledge), which indicates that non-compliance could be grounds for revocation of the patent. Obtaining a patent on a false suggestion or representation is also grounds for revocation under Section 64(1)(m).

In F Hoffmann-La Roche Ltd v Cipla Ltd [2015 (225) DLT 391] the court, interpreting Section 8 of the Patents Act, held that non-disclosure of the plaintiff’s US patent could not lead to rejection of the plaintiff’s suit because it did not cause prejudice and did not fail the test of ‘substantial compliance’ with the conditions prescribed by Section 8.

Courts may also refuse to award damages or accounts of profits in cases where the patent specification has been amended after publication of the application, for any use prior to the amendment, if the court is not satisfied that the specification as originally published was framed in good faith and with reasonable skill and knowledge.