Is It Inevitable? ‘Inherency’ in Australian Patent Law

One of the most fundamental requirements for an invention to be validly patentable is that it must be novel, i.e. new.  An invention lacks novelty or, in other words, is anticipated by a prior art  reference, only when a single reference discloses each and every element of the claimed invention.  If there is some difference between the claimed invention and the single reference, then the invention is novel – though it may nonetheless lack an inventive step if the difference is insignificant or would have been obvious to the skilled person.

Finding lack of novelty is straightforward when a prior art reference clearly and unambiguously discloses exactly the same thing that an inventor claims to have invented.  However, the situation can be more complex if the reference arguably contains an implicit or inherent disclosure of one or more elements of the claimed invention.

Questions of inherent disclosure most commonly arise in the chemical and pharmaceutical fields, particularly where an invention is based upon some newly-discovered property of a previously-known compound.  If the compound always had the ‘new’ property, and it is only that nobody had noticed, then can the invention be novel?

The issue of what, exactly, is ‘implicitly’ disclosed in a prior art reference arises in a decision of a full bench of the Federal Court issued on 23 January 2015 (Bristol-Myers Squibb Company v Apotex Pty Ltd [2015] FCAFC 2) in an appeal relating to a long-running dispute over the validity of a patent covering the antipsychotic drug aripiprazole.  The drug is marketed in Australia by Bristol-Meyers Squibb (BMS) as ABILIFY, under license from the patentee Otsuka Pharmaceutical Co., Ltd.

The Full Court has upheld the earlier finding of a single judge of the court that the patent is valid, notwithstanding that there is prior art teaching which, if carried out in a particular manner, could result in the claimed product.  On the other hand, it seems that there are many ways in which it could be carried out that would not result in the claimed product.

A ‘Doctrine’ of ‘Inherency’

In the United States the courts have developed a theory, or ‘doctrine’, of ‘inherency’ for considering such cases.  Section 2112 of the USPTO’s Manual of Patent Examining Procedure (MPEP) sets out the guidelines provided to US patent examiners for applying the inherency doctrine when assessing novelty.  These guidelines inform examiners that:

1. something which is old does not become patentable upon the discovery of a new property; and
2. there is no requirement that the skilled person would have recognized the inherent disclosure at the time of invention, but only that the subject matter is in fact inherent in the prior art reference.

This is all very well if an inventor is trying to claim a known product solely on the basis of a newly-discovered property.  But to what extent might this prevent the inventor from claiming a use or function of the product based on the previously unknown property?  The MPEP is equivocal on this point, stating ‘the claiming of a new use, new function or unknown property which is inherently present in the prior art does not necessarily make the claim patentable’ (my emphasis).

In other words: ‘it depends’.

There is a good reason for the non-committal guidance in the MPEP.  As well-known academic lawyers Dan Burk and Mark Lemley put it in the abstract to a 2005 paper:

Inherency is also perhaps the most elusive doctrine in all of patent law. The cases appear to flatly contradict each other, are often accompanied by dissents, and in the last three years alone have triggered one abortive en banc rehearing and strong calls for a second. In particular, the courts have split sharply over whether an element can be inherent in a prior art reference even if people of ordinary skill in the art do not appreciate the existence of that element.

In practice, the courts are no doubt simply trying to do justice to the facts in each case that comes before them.  Interestingly, Burk and Lemley conclude that the apparent inconsistency results from the courts’ focussing on ‘knowledge’ of the element when, in fact, what separates cases of inherent anticipation from those where novelty is found is not ‘knowledge’ but rather whether or not the public already has the benefit of the inherent element.

I say that this is interesting because it is an approach that aligns much more closely with the more clearly-stated position under Australian law, as I shall explain later.

The ‘Reverse Infringement’ Test

There is no doctrine of inherency in Australian patent law – or, at least, not one that is stated as such.

A key statement of the law of anticipation as it exists in Australia can be found in the decision of the English Court of Appeal in The General Tire & Rubber Company v. The Firestone Tyre and Rubber Company Limited and Others [1972] RPC 457 at 485-6; (1971) 1A IPR 121:

If the prior inventor’s publication contains a clear description of, or clear instructions to do or make, something that would infringe the patentee’s claim if carried out after the grant of the patentee’s patent, the patentee’s claim will have been shown to lack the necessary novelty, that is to say, it will have been anticipated. … if carrying out the directions contained in the prior inventor’s publication will inevitably result in something being made or done which, if the patentee’s patent were valid, would constitute an infringement of the patentee’s claim, this circumstance demonstrates that the patentee’s claim has in fact been anticipated.

If, on the other hand, the prior publication contains a direction which is capable of being carried out in a manner which would infringe the patentee’s claim, but would be at least as likely to be carried out in a way which would not do so, the patentee’s claim will not have been anticipated, although it may fail on the ground of obviousness. To anticipate the patentee’s claim the prior publication must contain clear and unmistakeable directions to do what the patentee claims to have invented…. (Emphasis added.)

For (hopefully) obvious reasons, this has become known as the ‘reverse infringement’ test.

Notably, knowledge of any inherent properties of the elements of the claimed invention does not enter into the analysis.  It does not matter whether the prior art expressly teaches every element of the claimed invention, or whether one or more elements are implicitly practised by following the teaching.  All that matters is whether the result would, or would not, necessarily fall within the scope of the later inventor’s claim.

Application to Aripiprazole ‘Crystals B’

In the most recent aripiprazole case, the full court was asked to review whether the judge in the original trial was correct to find that a prior art reference did not anticipate a claim directed to a particular preparation of aripiprazole having a specified crystalline structure (identified as ‘Crystals B’) and further characterised by specific physical properties.

The evidence (including experiments carried out by expert witnesses on both sides) confirmed that the prior art reference taught the skilled person to make aripiprazole and could, in at least some circumstances, result in Crystals B.  What was in dispute, however, was whether it was inherent in the reference to carry out further drying steps that would result in Crystals B, and all of the specific properties defined in the claim.

The court was satisfied that it was inherent in the prior disclosure that further drying steps would be required, however (at [50]):

As the primary judge said, the [prior art reference] did not dictate or teach any drying option. [Apotex’s expert witness] Associate Professor McGeary’s drying option, accordingly, was but one of many different approaches that a person skilled in the art might have undertaken had they wished to create the free base form of aripiprazole in accordance with Example 1 of the [reference]. While that option resulted in Crystals B, there was no evidence that any of the other drying options would have done so and an example in the patent suggested to the contrary.

Thus, the claim was not anticipated.

Conclusion – Similarities in US and Australian Outcomes?

The Australian legal test for ‘inherent’ anticipation has much in common with Burk and Lemley’s ‘public benefit’ test.  To illustrate with a hypothetical example, suppose that a particular formulation is known and used in the prior art as a moisturiser, and that someone subsequently discovers that it has UV protective properties.  An attempt to patent the formulation for use as a sunscreen would fail under the ‘reverse infringement’ test, because following the prior art directions to apply the formulation to the skin will inevitably result in the user being protected from UV rays.

Or, in Burk and Lemley’s terms, the public has already received the benefit of the new discovery, even though nobody knew it at the time.

On the other hand, if the new discovery is that the moisturiser formulation effectively repels aphids when sprayed in a fine mist on rose bushes, then the subsequent inventor of this use should be able to obtain a patent.  Following the prior art directions to apply the formulation to the skin does not inevitably (or even potentially, except in the most unlikely of circumstances) result in rose bushes with aphid protection!

Looking at this is Burk and Lemley’s terms, until the new discovery has been made, the public has not had the benefit of the previously unknown aphid-repellent properties of the formulation.

Just to be clear, I do not think that the two tests are exactly the same, nor that the ‘reverse infringement’ test will always produce identical outcomes to the US doctrine of inherency.  There may be, for example, cases in which the prior art reference offers only a very small number of alternatives – perhaps only two different ways of carrying out its teaching.  A strict application of the reverse infringement test would lead to the conclusion that following the instructions in the prior art will not inevitably lead to either one of the two possibilities, and thus there is no anticipation (although it is likely that the claim in question would be considered obvious in such as case).  I suspect that in the US, such a trivial case of alternatives might result in a finding of anticipation.

In Australia, however, the basic rule is quite simple – if it is inevitable, there is anticipation.

Tags: Australia, Infringement, Inherency, Pharmaceuticals, US