Can What You Say In Patent Examination Be Held Against You in Court?

Imagine that you have applied for a patent on an improved iron ore wagon.  During examination, you wanted to distinguish your invention from pre-existing ore wagons.  You therefore explained that your wagon has ‘an internal ridge’ that reinforces the side wall, and is ‘integrally formed within the side wall’, and you amended your claim to include this ‘integrally formed’ language.

Flash forward to a few years later, and you are in court arguing that one of your competitor’s iron ore wagons infringes your patent.  However, the competitor’s product has an internal ridge that is initially made separately from the side wall, and subsequently attached, e.g. by welding or riveting.  The court therefore has to decide whether this structure falls within the scope of the terminology ‘integrally formed within the side wall’.

This is, in a nutshell, the question that recently came before Justice Nicholas in the Federal Court of Australia (Bradken Resources Pty Ltd v Lynx Engineering Consultants Pty Ltd [2015] FCA 1100).  Interestingly, it raises four separate issues:

1. whether the term ‘integrally formed’, in and of itself, excludes the two-step constructions;
2. whether the amendment of the claims to include the ‘integrally formed’ language during examination informs interpretation of the term;
3. whether the applicant’s accompanying explanation of the advantages of the claimed structure should be taken into account when interpreting ‘integrally formed’; and
4. whether the patentee is now barred (or, in legal parlance ‘estopped’) from making a different argument in court to the one it made during examination.

To put it another way: to what extent can what the applicant did and said during examination of the application be held against it in a court of law?

The short answer is ‘somewhat’, but to nowhere near the extent it would be in some other jurisdictions, and in particular the United States.  And – spoiler alert – no, ‘integrally formed’ does not include something made in two parts and then joined together!

What Does ‘Integrally Formed’ Mean?

In Australia – as indeed in many other jurisdictions – the question of what a patent claim ‘means’ (i.e. its ‘construction’) involves a mixture of law and fact.  Ultimately the proper construction is for the court to decide, as a matter of law.  However, that construction must be considered from the perspective of the intended addressee of the patent specification, i.e. a person skilled in the relevant field of endeavour.  Typically, this involves presentation of expert witnesses experienced in the field, to inform the court about their understanding of the language used in the specification and claims.

As the court explained its task in the Bradken decision (at [53]):

The principal issue is whether the internal ridge referred to in claim 1 must be “formed” within the side wall of the bulk container in the technical sense of that word, when used in the context of metal fabrication, or whether it includes an internal ridge otherwise fixed (eg. by welding or riveting) to the side wall, so as to become a permanent part of the side wall. The answer to this question depends on what the words “... wherein said ... internal ridge is integrally formed within said side wall” mean when read in the context of the Specification as a whole.

After considering the patent specification, and the evidence presented on behalf of both sides, Justice Nicholas concluded (at [67]):

In my opinion the word “formed” and the phrase “integrally formed” as used in claim 1 refer to a piece of material that has been bent, pressed or moulded into shape.

Notably, this conclusion did not depend in any way upon the events that took place during examination of the application.

What is the Effect of Amendment?

Section 116 of the Patents Act 1990 provides that ‘[t]he Commissioner or a court may, in interpreting a complete specification as amended, refer to the specification without amendment.’

This essentially authorises a decision-maker to compare versions of the patent specification before and after amendment, if this will assist interpretation.  Note, however, that it does not go so far as to authorise looking at other materials, such as the applicant’s submissions accompanying an amendment.

In this case, the court observed that (at [82]-[84]):

Claim 1 in its original form requires that at least one side wall includes at least one ridge. Claim 1 in its amended form requires that there be an internal ridge integrally formed within the side wall. It is clear that the amendment narrowed the scope of claim 1.
…
The amendment to claim 1 strongly suggests that the new wording is to be understood to convey something more than that the ridge must be integral in the sense of being a permanent, or permanently attached, part of the side wall. In my view the amendment tends to confirm that, properly construed, claim 1 requires that the ridge and the side wall be “integrally formed” in the sense that they must be bent, pressed or moulded into shape from the one piece of material. (Emphasis in original.)

Note the court’s language: ‘…tends to confirm that…’.  That is, comparing the specification before and after amendment assists interpretation, in that it supports the conclusion that Justice Nicholas had already reached based on the intrinsic content of the final patent specification in light of the experts’ evidence.

‘Prosecution History Disclaimer’

In the United States, what you say during examination of a patent application can definitely be later held against you in a court of law.  Regarding the interpretation of claim language, the relevant doctrine is usually called ‘prosecution history disclaimer’.  (‘Prosecution history’ is the technical term for the written record of examination of an application.) 

This doctrine was recently reviewed by the US Court of Appeals for the Federal Circuit in Shire Dev., LLC v. Watson Pharma., Inc., No. 13-1409 (3 June 2015).  In particular, subject to certain checks and balances,

In addition to the specification, this court looks to the prosecution history. For example, “where the patentee has unequivocally disavowed a certain meaning to obtain his patent, the doctrine of prosecution disclaimer attaches and narrows the ordinary meaning of the claim congruent with the scope of the surrender.” Omega Eng’g, Inc. v. Raytek Corp., 334 F.3d 1314, 1324 (Fed. Cir. 2003); see Ekchian v. Home Depot, Inc., 104 F.3d 1299, 1304 (Fed. Cir. 1997) (“since, by distinguishing the claimed invention over the prior art, an applicant is indicating what the claims do not cover, he is by implication surrendering such protection”).

This is not the position in Australia, where the Federal Court has adopted, with some gusto, the reasoning of Lord Hoffman in the English case of Kirin-Amgen Inc v Hoechst Marion Roussel Ltd [2004] UKHL 46, who said (at [35]):

The courts of the UK, the Netherlands and Germany certainly discourage, if they do not actually prohibit, use of the patent office file in aid of construction. There are good reasons: the meaning of the patent should not change according to whether or not the person skilled in the art has access to the file and in any case life is too short for the limited assistance which it can provide.

(I note that while this argument carries some rhetorical force, it is not factually persuasive, in that the US currently ranks equal 34th in the world by life expectancy, alongside Colombia, Nauru, Costa Rica, Cuba and Qatar, while the UK ranks equal 19th, and Australia equal 2nd.  So if anybody has time to read the patent office file it is Australians, not Americans!)

Or, as Justice Nicholas explains in the Bradken case (at [86]):

I do not think the patent attorney’s letter is admissible evidence as to the proper construction of claim 1. The reasons why are apparent from the passages in the speech of Lord Hoffman in Kirin-Amgen to which I have previously referred and the reasons of Gummow J (with whom Northrop J agreed) in Prestige Group (Australia) Pty Ltd v Dart Industries Inc (1990) 26 FCR 197 (Prestige). As Gummow J observed at 213, the scope of the monopoly depends upon the proper construction of the claims read in the context of the specification as a whole and in light of the common general knowledge. The authorities in this country have eschewed recourse to extrinsic materials (such as correspondence between the patent applicant and the Commissioner) for the purpose of ascertaining the true scope of a claim.  (Emphasis added.)

‘Prosecution History Estoppel’

It is one thing to say that the patent office file cannot be used in working out what the patent claims mean, and another to allow the patentee to turn up in court and make an argument that is inconsistent with – or even directly contradicts – something that it said in an effort to secure a patent in the first place.

In the United States, for example, the doctrine of prosecution history estoppel (a.k.a. ‘file wrapper estoppel’) prohibits a patentee from taking advantage of the doctrine of equivalents (a mechanism allowing for a broader interpretation of terms in a patent claim) if they had previously made corresponding narrowing amendments, in order to overcome prior art.  In other words, the patentee cannot have their cake and eat it, by saying one thing in order to obtain a patent in the first place, and then saying something else in order to capture a broader range of infringements.

Whether or not some form of prosecution history estoppel applies in Australia remains an open question, however it is one that the courts have regarded as presenting difficulties that have generally resulted in it being relegated to the ‘too hard’ basket.  In Prestige Group (Australia) Pty Ltd v Dart Industries Inc [1990] FCA 281 Gummow J stated (at [35]) that:

…in my view there appear to be significant difficulties in founding "file wrapper estoppel" in either the law of evidence as to admissions or in the law as to estoppel by representation as they are presently understood in this country. But I would not regard the issue of the role of "file wrapper estoppel" in this country as other than still open for decision.

In Bradken, Justice Nicholas has cited the above passage from Prestige and further stated (at [90]):

Although the applicability of the US doctrine of “file wrapper estoppel” may not have been settled by the Full Court’s decision in Prestige, the observations of Gummow J in that case highlight the considerable obstacles that are involved in applying the doctrine in this country. The Bradken parties were unable to point to any developments in the law since Prestige was decided that might suggest that these obstacles are now any less weighty than Gummow J’s reasons suggest them to be.

Generally speaking, then, patentees in Australia have not been barred from revisiting issues addressed during examination, or even from making new and/or different arguments in court.  While this might seem strange to some people, there are a couple of reasons why it is unlikely to result in any real harm.

Firstly, if the arguments made during examination were consistent with the language of the specification and claims at the time, then the circumstances in which a court might be persuaded by a substantially different argument in relation to the same language are likely to be limited.

Secondly, Australian patents do not enjoy any presumption of validity.  Arguing for a broader interpretation of a claim that was narrowed in order to overcome prior art that the examiner regarded as depriving the invention of novelty or inventive step is therefore a risky strategy.  While a broader claim is more likely to be infringed, it is also more likely to be invalid!

Conclusion – Claims Mean What They Say… to the Skilled Person

In summary, under Australian law:

1. claims mean no more, and no less, than what they say – bearing in mind that they must be viewed from the perspective of a person with skills and knowledge of the relevant field, and not simply the ordinary person off the street;
2. section 116 of the Patents Act permits recourse to earlier versions of the patent specification – and thus, in effect, to amendments made – to assist interpretation;
3. however, it is not permissible to look to other extrinsic material, such as arguments submitted during examination of the patent application, when interpreting the scope of patent claims; and
4. no Australian court has ever applied a doctrine of prosecution history estoppel – despite having been urged to do so on a number of occasions – and there are no signs that this is likely to happen in the foreseeable future.

Overall, then, interpretation of patent claims is relatively straightforward in Australia.  The problem, however, is that this is only because we are comparing with jurisdictions such as the US where it can be horrendously complicated!

Tags: Claim construction, Estoppel, Examination