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Mayne v Debiopharm: Inventive Step, Sufficiency and the Skilled
Person – who is skilled in the art and what do they know?
Mayne v Debiopharm
In May 2006, Mr Justice Pumphrey gave judgment in the Mayne v Debiopharm case [1], which concerned the validity of two patents relating to oxaliplatin, and the infringement of one of them. In that case, he had to consider the attributes and identity of the ‘skilled person’, by reference to whom a patent’s validity may be determined. The nature of the ‘skilled person’ is a key issue for generic companies in evaluating whether or not a patent is valid, or may be revoked.
Patent Validity
In order to be valid, a patent must involve an inventive step. It will do so if the claimed invention
‘it is not obvious to a person skilled in the art, having regard to any matter which forms part of the state of the art…’[2].
If a patent does not contain an inventive step, it can be revoked, as can a patent in which
‘the specification … does not disclose the invention clearly enough and completely enough for it to be performed by a person skilled in the art’[3].
Who is the skilled person?
Who is the ‘person skilled in the art’, by whose abilities a patent will stand or fall? Well, like ‘the man on the Clapham Omnibus’, and ‘the reasonable man’, a legal fiction. A person without inventive ability, rather dull, but with appropriate knowledge. In the words of the UK Patent Office
‘the skilled person should be taken to be a worker who is aware of everything in the state of the art and who has the skill to make routine developments but not to exercise inventive ingenuity. The "person skilled in the art" may be a multi-disciplinary team rather than a single individual’[4].
I’d rather make friends with the man on the Clapham Omnibus…
Oxaliplatin
Oxaliplatin is a ‘third generation’ platinum-based compound for cancer therapy, the first and second generations being represented by cisplatin and carboplatin, launched in 1979 and 1986 respectively. Oxaliplatin itself was launched in 1999, its existence having been disclosed in 1976, and the patents in issue were ‘second generation’ patents covering improvements to the already known product.
Debiopharm argued that the patent was addressed to an ordinary organo-chemist, who would not have knowledge of existing platinum-based compounds for cancer therapy, but the judge disagreed:
‘those primarily interested will be employees of pharmaceutical companies interested in improving or making for the first time, oxaliplatin. Chief among those would be those who have already made oxaliplatin, carboplatin or cisplatin…It is not sensible not to attribute to the skilled person the common general knowledge of those presently engaged in the manufacture and formulation of platinum-based pharmaceuticals.’
This seems utterly reasonable, and something for you to bear in mind when trying to evaluate whether or not a particular patent is valid – you are entitled to assess inventive step and sufficiency by reference to the skills of the person or team who would have been most interested in the relevant field at the time of the application.
Enabling disclosure
Under English law, the ‘skilled person’ has imputed to them what was common general knowledge at the priority date of the application. In this particular action, the judge decided that that would include a ‘proper understanding’ of the chemistry of platinum-based compounds – and in this case, that was enough to render the patent invalid. The steps claimed by the patentee, would have been obvious, the judge considered. Further, the patent was anticipated by a prior publication, ‘Kidani’, an ‘enabling’ disclosure which was sufficient to disclose the claimed invention to the skilled person. Kidani disclosed a method of synthesis that would ‘ enable a skilled person wishing to achieve success rather than failure to make oxaliplatin without undue expenditure of time and effort and without undue experimentation’. It satisfied the test for sufficiency set out in the leading case, Valensi v BRC[5], in which it was said that
‘the hypothetical addressee is not a person of exceptional skill and knowledge,... he is not to be expected to exercise any invention, nor any prolonged research, enquiry or experiment. He must however be prepared to display a reasonable degree of skill and common knowledge of the art in making trials and to correct obvious errors in the specification, if a means of correcting them can readily be found’
Provisions as to the time the skilled person must expend, before a disclosure will be regarded as insufficient, to which,
‘clearly there must be a limit…the patent specification ..can leave the skilled man to use his skill to perform the invention…He may need to carry out the ordinary methods of trial and error, which involve no inventive step…In each case it is a question of fact, depending on the nature of the invention, as to whether the steps needed to perform the invention are ordinary steps of trial and error which a skilled man would realize would be necessary and normal to produce a practical result.[6]’
Identify the skilled person
It is vitally important to determine the nature of the identity of the ‘skilled person’ in any action relating to the validity of a patent by reference to inventive step, or sufficiency. Depending on the nature of this person (individual or team), the patent may stand or fall. Many products which are attractive candidates for generic companies fall within known classes of products - and knowledge which relates to that class can be regarded as belonging to the skilled person, and used to attack the validity of patents on a later product or formulation. It is also worth remembering that your expert, who will give evidence as to what the skilled person would have known at the priority date, is not, and never was, the skilled person – he is likely to be more creative than that fictional character – fortunately perhaps, since a close working relationship with the skilled person would be a rather dull affair.
[1] 1) Mayne Pharma Ltd v (1) Debiopharm SA (2) Sanofi-|Symthelabo (2006) [2006] EWHC 1123 (Pat)
[2] Patents Act 1977 s3
[3] Patents Act 1977 s72 (1) (c)
[4] Genentech Inc's Patent [1989] RPC 147 (Court of Appeal) Chiron v Organon Teknika (No. 3) [1994] FSR 202 (Patents Court) Havard / Fusion proteins OJEPO 1992, 268 (T0060/89)
[5] Valensi v BRC [1973] RPC 337 at P 377 (CA)
[6] Mentor v Hollister [1993] RPC 7 at P 14
Anna McKay
August 2005
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