Opposition Succeeds as Claimed Polymorph No Different to Prior Art, Based On ‘Gold Standard’ Comparison

Wrays Solutions Pty Ltd v Zhejiang Zhuji United Chemicals Co., Ltd. [2024] APO 44 (29 October 2024)

Highlight

In a straw man opposition, Wrays Solutions (Wrays) has successfully opposed all claims (apart from claim 11) of AU2019446196 (the Patent Application) held by Zhejiang Zhuji United Chemicals (Zhejiang).  The opposition to the grant of the Patent succeeded on the grounds of novelty (claims 1, 2 and 9), inventive step (claims 1, 2, 9 and 10), clarity (claim 2), utility (claim 3) and lack of support and sufficiency (claims 3 to 7).  While Wrays filed expert evidence in support of its opposition, Zhejiang filed no expert evidence, relying solely on legal submissions to answer the opposition.  Zhejiang was given two months to propose amendments.  Zhejiang has appealed the opposition decision to the Federal Court of Australia, and in those proceedings has given notice that it intends to seek to amend the Patent Application.  Zhejiang now has until 20 March 2025 to file an application in the Federal Court proceedings for an order for amendment of the Patent Application.

The Patent Application claimed an allegedly new high-purity thermostable crystalline form, or polymorph, of an existing herbicide, bixlozone, detailing its space group, lattice parameters and melting point.  The claims also covered the crystal structure with a specific powder X-ray diffraction (PXRD) pattern, methods for preparing it using specific solvents and conditions, and its application in agrochemical formulations.

Key Issues

Construction – Melting Point Temperature Range

One of the key disputes between the parties that impacted several of the grounds related to the claimed melting point temperature range of 83°C to 85°C in claim 1.  Wrays argued that the skilled person would not understand the defined temperature range of 83°C to 85°C to be a hard and fast cut-off.  Zhejiang disagreed, arguing that the claimed temperature range was based on their experimental results and already factored in a margin for experimental error.  While the Delegate noted that the claimed lower limit was set at the precise temperature of one of the exemplified products in the specification, the Delegate ultimately concluded that the specific upper and lower limits of the temperature range were essentially arbitrary.  Further, the Delegate considered that, based on the terminology used in the claim, the temperature range defined in claim 1 would be understood as being 83°C to 85°C.  There was no qualification or imprecision imposed on the defined range, either explicitly in the claim or implicitly through any definition given in the specification or purposive reading by the skilled person.

Novelty

At the hearing, Wrays argued that claims 1, 2 and 9 to 11 were anticipated by WO2019030177 (D1), or alternatively, in light of the combination of D1 and US4405357 (D2).  The Delegate found claims 1, 2 and 9 to lack novelty in light of D1 on the basis that:

1. D1 disclosed the polymorph claimed in claims 1 and 2.  On this point, the Delegate noted that the PXRD patterns were relevantly identical, even though D1 did not disclose the claimed melting point range.  The Delegate accepted Wray’s expert evidence which established that two different polymorphs of the same material could have similar melting points, but stated that the suggestion that two different polymorphs could have almost identical PXRD was not plausible based on the expert evidence as well as the data derived from Zhejiang’s own experiments.
2. D1 also enabled the skilled addressee to be able to make the polymorph defined by claims 1 and 2.  On this point, the Delegate stated that it was not enough for the prior art simply to disclose the invention – it must also enable the invention.  The Delegate therefore analysed the disclosure in D1 to determine (and ultimately conclude) that, following the instructions given in D1, a crystal according to claims 1 and 2 would inevitably be obtained.

The Delegate found that D1 did not anticipate claims 3 to 7, 10 and 11 as the specific methods defined by these claims were not disclosed by D1.

Inventive Step

Wrays argued that the invention claimed in claims 1, 2 and 9 to 11 were obvious is light of the common general knowledge in combination with D1 alone or D1 together with D2.  As the Delegate had found that the inventions in claims 1, 2 and 9 lacked novelty, the Delegate considered that it followed that they were also obvious.  So, the Delegate limited his consideration of this ground to claims 10 and 11.

The Delegate found claim 10 to be obvious.  The Delegate considered that the skilled person would arrive at the claimed combination of formulation and use defined in claim 10 without the exercise of any inventive faculty and in the expectation that it would provide a useful result.  In reaching this conclusion, the Delegate relied on the fact that the replacement of one form of bixlozone with another in known herbicide applications would present no apparent difficulty or barrier to the person skilled in the art.

The Delegate did not, however, find claim 11 to be obvious, stating that based on the evidence before him he was unable to conclude that the specific use of the claimed formulations of bixlozone in wheat or corn was a mere choice from a number of equally useful alternatives that would have been obvious to the skilled person at the relevant time.

Clarity

Wrays argued that claim 2 was unclear because relative peak intensity was one of the parameters used to define the claimed polymorph.  Wrays argued that, as the relative intensities of peaks in a PXRD spectrum will depend on a range of factors during sample preparation, the same crystal form might show different intensities for peaks in its PXRD depending on how the sample was prepared.  This meant that the skilled person would not know whether a crystal form they had produced would fall within the scope of claim 2, particularly given that the Patent Application provided no guidance as to what relevant parameters should be used in the sample preparation for producing the required spectrum.

The Delegate agreed, finding that claim 2 lacked clarity, noting that:

• the evidence showed that peak intensity was not a reliable means of distinguishing between polymorphs because of orientation effects and sample preparation effects; and
• if an unusual or “special” parameter was used in a claim to characterise an invention, then detailed information must be given to enable the skilled person to determine whether they were working within the scope of the invention.  This would include sufficient information such that any factors, including orientation effects and sample preparation effects, could be taken into account in the comparison.  Without these details the skilled person would not be able to determine with any certainty whether they were working within the scope of claim 2.

Sufficiency and Support

The Delegate considered claims 3 to 7 to be insufficient and lacking support.  Section 40(2)(a) of the Patents Act requires that the complete specification must disclose the invention in a manner which is clear enough and complete enough for the invention to be performed by a person skilled in the relevant art.  Section 40(3) requires that the claims are supported, that is, that the extent of the patent monopoly, as defined by the claims, should correspond to the technical contribution to the art in order for it to be supported, or justified.

The Delegate considered that claims 3 to 7 were both insufficient and lacked support because of the limited teaching in the Patent Application regarding how to make the seed crystal from which the claimed polymorph would be recrystallised.  The specification taught the preparation of the seed crystals using only a specific method and specific conditions.  This limited teaching did not enable the invention claimed in claims 3 to 7 to be performed across the breadth of the claims.  It also followed that the method claims in claims 3 to 7 exceeded this limited technical contribution in the specification.  In reaching this conclusion, the Delegate considered that the evidence showed that:

• the conditions required to obtain the seed crystal were more specific than the general process of simply heating, cooling and re-heating in order to obtain the specific mixture of polymorphs in the specific arrangement; but
• once the seed crystal was obtained, the skilled person would be able to determine appropriate conditions and solvents for its use in recrystallization by routine trial and error.

Utility

The Patents Act requires that a claimed invention be useful.  This means that an invention must do what it is intended by the patentee to do, in that it meets the promise of the invention.  Wrays argued that the invention claimed in claim 3 was not useful as claim 3 required a solvent selected from “alkanes and cycloalkanes”, but the specification stated that hexane, an alkane, would not perform the method of the claim.  The Delegate agreed with Wray’s submission, on the basis that it included matter that did not work, and for which the specification did not provide additional information by which the skilled person could make the process work.

Outcome

Wrays succeeded in opposing the grant of all claims except claim 11.  Zhejiang was given two months from the date of the decision to propose amendments.  Costs were also awarded against Zhejiang.

Implications

The decision of the Patent Office provides guidance on a number of key areas.

On novelty, the Delegate’s decision reinforces that a prior art document can anticipate a claimed invention where the features of the claimed invention are inherent (although not explicitly disclosed) in the prior art document.  This led the Delegate to find that D1 anticipated the claimed polymorph based on identical PXRD patterns, despite not disclosing the melting point range.  For inventive step, the decision emphasises that the mere substitution of equivalents lacks inventiveness unless it yields unexpected results, finding that replacing one bixlozone form with another in herbicide applications was an obvious choice.  However, claim 11 survived as its specific use in wheat and corn was inventive.

Regarding clarity, the decision underscores that claims relying on specialised parameters (like PXRD peak intensity) must provide enough detail for skilled persons to determine whether they fall within the claim.

On sufficiency and support, the decision confirms that broad claims must be justified by the patent’s technical contribution, finding that the limited teaching on seed crystal preparation meant claims 3-7 could not be performed across their full scope.

Finally, on utility, the decision reinforces that claims covering inoperative embodiments lack utility.  Claim 3 failed as it encompassed solvents (like hexane) that the specification admitted would not work, without explaining how to fix the issue.

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