Australian patent practice note: Recent changes to examination practice for claims to crystalline polymorphs


The Australian Patent Office appears to have recently changed their examination practice regarding the support requirements for claims directed to crystalline polymorphs. Given that we have not yet seen any update to the Examiner’s Manual to explain this practice change, we understand that it is informal at this stage.

Previously, it may have been possible to claim a crystalline polymorph by reference to even a single characteristic X-ray diffraction peak. According to this new practice, some Examiners are now requesting that claims recite at least the ten strongest peaks for each polymorph, and in some cases, even requesting that the claims recite the relative intensities of the peaks.

Some Examiners are helpfully issuing detailed reasoning to explain the basis for these requirements. For example, Examiners have been making reference to textbook references regarding characterisation of pharmaceuticals such as “Polymorphism in Pharmaceutical Solids”, Brittain, H.G. ed., 2009 and the United States Pharmacopeia and asserting that it is generally accepted that XRPD characterisation of a polymorph may be established if at least the ten strongest scattering angles agree to within 0.2º, and possibly also that their relative intensities do not vary more than 20%.

We understand that another rationale for this new practice is that Examiners are aware that even very small changes to characteristic XRPD peaks can result in the definition of an entirely different polymorph, having different properties. In this regard, Examiners have informally commented to us that the new practice in relation to polymorphs is analogous to the manner in which claims to alloys are examined.

Nevertheless, our understanding is that Examiners are requiring the identity of claimed crystalline polymorphs to be specified to what seems to be a very high standard. It seems that in at least some circumstances it may be possible to adequately define a polymorph with reference to fewer scattering angles. It must be kept in mind that these objections are being raised on the basis that the claims are not “supported by matter disclosed in the specification” (as required by section 40(3) of the Australian Patents Act 1990), and to meet the support requirement the claims should ‘essentially correspond to the scope of the invention as disclosed in the description. In other words, the claims should not extend to subject-matter which, after reading the description, would still not be at the disposal of the person skilled in the art’ (Generics (UK) Ltd v H Lundbeck A/S [2009] RPC 13 at [36], affirming T 409/01).

We are yet to see if Examiners will be open to hearing arguments regarding these new requirements, or if they will survive challenge in a hearing (either before the Patent Office or perhaps eventually the Court). We will be monitoring any changes in this area.

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