The Best Method

1Section 10(4)(b) of the Patents Act requires the specification to disclose the best method of performing the invention that is known to the applicant, for which he is entitled to claim protection. Under s 64(1)(h), non-disclosure of the best method is made a ground for revocation of a patent. The language used in the above sections indicates that the applicant is obliged to disclose the best method only if he is entitled to claim protection for the same. If the best method was already known, and consequently the applicant had not claimed protection, non-disclosure of the best method cannot be a ground for revocation of a patent.

2The requirement of disclosure of best method still figures in the Patents Act though it has now been omitted from the UK Patent Act 1977. Proving the fact that the complete specification did not disclose the best method will be difficult, as the disclosure will be deemed to be the knowledge that was available to the applicant on the date of filing the complete specification. The above ground of revocation requires that the best method be known to the patentee. It follows that a thing that is 'known' would be 'something of which the result is certain and established so that it can properly be concluded that if it is not disclosed the patentee has defrauded the public and that there is no proper consideration for the grant'. (See Monsanto Co v Maxwell Hart (London) Ltd (1981) RPC 201, p 242.) The above ground is not confined to dishonest conduct of the patentee, it is available for 'any case in which the applicant has not disclosed in his complete specification the best method known to him of performing the invention, whatever the reason for the omission'. (See Du Pont De Nemours & Co v Enka BV [1988] FSR 69, p 89.) A petitioner for revocation under this ground, however, need not allege or prove that a particular method was known to the patentee at the date of his application or at any other particular date. (See Polaroid Corpn's Patent [1977] FSR 233, p 241 (CA).)

3Whether best method requirement is satisfied is a matter that requires evidence in trial and the court may not come to a conclusion in the interim stage. In Merck Sharp and Dohme v Glenmark Pharmaceuticals (2015) (para 54) the Division Bench observed, in an interlocutory proceeding, that it was not clear if the obligation under section 10 (4)(b) stood breached and refused to consider it as a factor that would disentitle Merck the interim relief it prayed for.