1A best method challenge under s 40(2)(aa) of the Patents Act 1990 may be sufficiently arguable at the interlocutory stage where the specification promises industrial-scale advantages but discloses only laboratory-scale examples, and there is an evidentiary foundation (including evidence of the patentee's commercial manufacturing activities proximate to the filing date) from which knowledge of an undisclosed industrial process can be inferred, even without identifying the undisclosed method with precision (applying Zoetis at [65]).
2Where a misleading or deceptive conduct claim is based on silence or failure to warn rather than an express representation, the material facts giving rise to the alleged representation — including the relevant class of purchasers, transactions, communications or circumstances — must be pleaded, not merely the bare allegation that any supply without a warning conveys the representation.
3Overlap between a proposed new invalidity ground and existing pleaded issues (such as utility, sufficiency and infringement) is a relevant discretionary factor favouring the grant of leave to amend, particularly where the additional trial burden is modest (applying Juno Pharmaceuticals at [83]–[86]).
