From the time of the Statute of Monopolies 1623, 21 Jac 1, c 3 ('Statute of Monopolies'), the flexible concept of a 'manner of manufacture' was understood to involve some form of limitation which was expressed in the statute as being 'mischievous to the State - or hurt of trade, or generallie inconvenient'.1 Years of judicial consideration resulted in various classes of subject matter being carved out as unpatentable. Apart from noncontentious material such as discoveries, ideas and principles of nature, these classes included methods of medical treatment for humans, horticultural and agricultural methods, computer programs, presentations of information, plans and business schemes.2 The classes were relatively clear by 1959 when the High Court in National Research Development Corporation v Commissioner of Patents3 was asked to judge thepatentability of an invention in an excluded class, namely a horticultural method. The trouble was that there were no consistent rationales to justify the excluded classes and to distinguish patentable from non-patentable subject matter. The High Court faced the quandary squarely, dismissed the proposition that horticultural and agricultural methods are unpatentable as a class and opened the way for future courts to approve the patentability of inventions that fell within this and other formerly excluded classes.4 In consequence of NRDC, the mere fact that an invention may be called amethod for medical treatment, a business method or a plan or scheme, for example, no longer prevents it being properly the subject of a patent.