There is an institutionalised tension in the European patent law relating to the construction of patent claims. It is a tension that results from the European patent law's ideal of ensuring that a patent, when granted, will give proper and fair breadth of protection to the patent holder, while at the same time ensuring that the general public will be clear and certain about the precise scope of that protection. This ideal can be seen as requiring an approach to construction that is positioned midway between two otherwise irreconcilable imperatives; an approach which is not susceptible of any more precise definition.
From an English perspective, the tension is enshrined in the wording of §125 of the Patents Act 1977 (which statutorily defines an invention for patent purposes; and which is framed to correspond, and be consistent, with Article 69 of the European Patent Convention (the EPC)), and in the Protocol on the Interpretation of Article 69 of the EPC (the Protocol), which is applicable to §125. §125 provides that an invention shall, unless the context otherwise requires, be taken to be that specified in a claim as interpreted by the description and any drawings contained in the specification. The Protocol calls for such interpretation of a claim to achieve what it describes as a position combining "fair protection for the patentee with a reasonable degree of certainty for third parties".
Fair protection for the patentee envisages that the courts will provide protection from infringement where a defendant's product/process/method does not literally infringe the claims of the patent in suit, but rather takes the essence, or materiality, of the inventive concept. On the other hand, reasonable certainty for third parties requires that the public, or a competitor, can know with appropriately diligent and professionally advised enquiry what the boundaries of the patentee's protection are.
Currently, in continental Europe it is possible to say that, notwithstanding that the patent laws are drafted with the goal of uniformity in mind, their interpretation and application are divergent and uncertain. The institutionalised tension in the EPC was intended to reflect and address the previous polarity of the approaches taken by the English and German courts to the construction of patent claims. Would that the position now in England were susceptible to as straightforward an analysis and explanation as that might suggest. In fact, as this article will seek to identify, the English law of construction has become so muddled and confused by the apparent change of emphasis which the Protocol and other European inspired legislation has caused, that it is almost impossible simply to define what the current position is. To require, as the Protocol does, reasonable certainty for third parties is to suggest that interested parties such as competitors can, with reasonable enquiry, predict whether what they propose falls within the penumbra of any relevant claim.
Background to the English approach
The current approach of the English Courts is perceived to flow from Lord Diplock's judgment in the case of Catnic Components Ltd and Another v Hill and Smith Ltd [1982] RPC 183. Lord Diplock was there addressing the question of whether individual descriptive words and phrases appearing in claims should be construed strictly and literally, or whether (and, if so, to what extent) they should be construed in a somewhat broader, more figurative, way. He said that the approach to such questions of construction in each case should be to ask whether the addressee of the patent (the skilled man) "...would understand that strict compliance... [with such descriptive words or phrases]... was intended by the patentee to be an essential requirement of the invention so that any variant would fall outside the monopoly claimed, even though it could have no material effect upon the way in which the invention worked".
Lord Diplock's direction with regard to the way that patent construction was to be approached was delivered in relation to a pre-1977 patent (which therefore fell to be construed under the then existing common law principles, and not with regard to the statutory requirements of the 1977 Patents Act, and the Protocol). That direction was, nevertheless, taken by Hoffmann J some nine years later, used in the construction of a patent to which the 1977 Patents Act did apply, and formulated into what have become known as the "Improver Questions". In Improver Corporation and Others v Remington Consumer Products Limited and Others [1990] FSR 181, the seminal case, Hoffmann J reduced Lord Diplock's analysis of the way patent construction should be approached into three questions:
Does the variant have a material effect on the way that the invention works? If yes, the variant is outside the claim. If no:
Would this have been obvious at the date of publication of the patent to the man skilled in the art? If no, the variant is outside the claim. If yes:
Would the reader skilled in the art nevertheless have understood from the language of the claim that the patentee intended that strict compliance with the primary meaning was an essential requirement of the invention? If yes, the variant is outside the claim.
The Improver Questions have since been adopted and used by the English Courts in determining questions of construction under the 1977 Patents Act. Indeed, they have recently been re-affirmed and, one might say, re-branded as the "Protocol Questions" by Aldous LJ by in Wheatley v Drillsafe [2001] RPC 133. The Improver/Protocol Questions have been followed on the twofold assumption that, first, they reflect and represent Lord Diplock's analysis of the approach that should be taken to the construction of patent claims, and that, second, Lord Diplock's speech in Catnic indicated the same approach to construction as that laid down in the Protocol.
There is, however, a basis for arguing that both of these assumptions are wrong. For the purposes of this article, I propose only to deal with the first of the assumptions.
In this context, it is only necessary to analyze the third of the three Impover/Protocol questions. It is this question which purports to reflect the approach to construction indicated by Lord Diplock, and the first two of the Improver/Protocol questions can be ignored for these purposes.
Catnic v Improver [2001]
Upon analysis, then, how closely does the third Improver/Protocol question in fact mirror the question posed by Lord Diplock about the understanding of the man skilled in the art? When his judgment is examined closely, it is apparent that Lord Diplock does not, in fact, call for the question of what the skilled man understood the patentee to mean to be answered by reference to "the language of the claim". In the Catnic case, the point at issue was whether a patent for galvanised steel lintels, which called for a vertical back plate to the lintels, was infringed by lintels that had a back plate 6º off the vertical. In his judgment, Lord Diplock analyzed the speeches of the House of Lords in three earlier cases; Van Der Lely v Bamfords, Rodi and Weinenberger AG v Harry Showell Ltd and Beecham Group Ltd v Bristol Laboratories Ltd. For the purposes of this discussion, his comments on the last of these three cases is, perhaps, the most illuminating. He said:
This House unanimously held [in the Beecham Group Ltd v Bristol Laboratories Ltd case] that this temporary masking of the amino group amounted to an immaterial variant. It would be obvious to anyone skilled in the specialised art of selecting and synthesising polymers for use as antibiotics that the essential feature of the invention was that when put to use for its intended purpose, the product should have an amino group in the alpha position; and that, accordingly, the patentee's reference to this feature of his claim cannot have been intended by him to exclude products in which the amino group in that position was temporarily displaced.....
Consistent with that line of jurisprudence to the effect that the teaching of the patent, in appropriate cases, informed the construction of particular words and phrases in patent claims, Lord Diplock went on put the question that he considered to be before him in the Catnic case "in a nutshell":
Would the specification make it obvious to a builder familiar with ordinary building operations that the description of a lintel in the form of a weight-bearing box girder of which the back plate was referred to as "extending vertically" from one of the two horizontal plates to join the other, could not have been intended to exclude lintels in which the back plate although not positioned at precisely 90° to both horizontal plates was close enough to 90° to make no material difference to the way in which the lintel worked when used in building operations?
Lord Diplock, noting that no plausible reason had been advanced as to why any rational patentee would want to so limit his invention, answered his own question in the following terms:
...the expression "extending vertically"... is perfectly capable of meaning positioned near enough to the exact geometrical vertical to enable it in actual use to perform satisfactorily all the functions that it could perform if it were precisely vertical... (emphasis added)
Lord Diplock said, in his judgment, that he did not think it helpful to undertake a line by line analysis of the way that specific words and expressions were used throughout a patent. Moreover, it can be seen that the approach that Lord Diplock took was, having identified and analysed the function and working of the Catnic patent, to ask whether the patentee intended to exclude, from its patent claims, a lintel having a backplate 6° off vertical.
What may legitimately be distilled from Lord Diplock's decision is that identifying the primary acontextual meaning of a particular word or phrase is not the end of the enquiry. Otherwise, "vertical" would always mean "vertical" ? and nothing more. What Lord Diplock reasoned was that, in establishing the meaning and the construction of a claim, it was necessary to identify whether the patentee had provided a "code", or "map" for the understanding of the purpose or rationale of a particular word or phrase. In such circumstances, where the patentee through its description and drawings had taught the function of the integer to which the word applied, protection was not to be withdrawn merely because the defendant has used something which did not accord with the acontextual meaning of the word or phrase under scrutiny. In other words, the key to the code was to be found in the patentee's teaching. From this, the perfectly reasonable assumption to be drawn is that, if the patentee does not teach appropriately, the scope for construction beyond the acontextual meaning is significantly limited.
As noted earlier, it has generally been accepted that the Improver/Protocol Questions represent Lord Diplock's approach to construction in algorithmic form, and they have been applied on that basis by the courts in the UK since their formulation by Hoffmann J. In that form, they are used by the courts in the UK as an aid to arriving at what it is agreed should be a purposive and contextual interpretation of any patent in suit.
However, the way in which the third of the questions has been framed does, in fact, reflect a subtle, but very significant, departure from the approach taken by Lord Diplock.
In Improver, the plaintiffs claimed infringement of their "Epilady" patent by the defendants on the basis that the defendant's product was effectively a mechanical equivalent. Hoffmann J found that the defendant's rubber rod, with slits, operated in the same way as the plaintiff's helical spring. However, the judge found the patent not to be infringed, limiting his analysis to asking whether a "rubber rod" was a "helical spring", rather than asking whether the teaching of the patentee was that the helical spring was not claimed for itself, but rather for its properties when used in a particular way. (Moreover, the plaintiff's patent specifically stated that the patentee did not intend to limit itself to any particular hardware in its claims, but claimed anything that produced the same functional result).
In the author's submission, Hoffmann J, far from following Lord Diplock's analysis, actually disavowed it. Hoffmann J's formulation of the third Improver/Protocol question reflects an emphasis on the "language of the claim", and an assumption that a variant is not within a claim unless the patentee specifically intended to include it; neither of which is warranted by reference to Lord Diplock's judgment. The continuing use of that question by the English courts as an aid to patent construction, perpetuates that anomaly.
Help please!
The resulting inherent state of confusion with regard to claim interpretation is starkly illustrated in the difference in the approach taken by the courts in certain cases, such as the recent cases Taylor v Isheda (Europe) Ltd and Another, and Amersham Pharmacia Biotech AB v Amicon Limited and Others, where close regard appears to have been had to the extensive teaching in the patent specifications when construing the patents in suit, and cases such as Dyson v Hoover, where the term "frusto-conic" (literally requiring straight, converging, sides) was construed to include "trumpet shaped", notwithstanding the absence of any significant teaching in the patent to support this. (In the Dyson case, it is also worthy of note that this construction was arrived at notwithstanding that both parties' experts agreed that any variation from a straight-sided cone could have material and unknown effect).
Since virtually all English patent judges claim to be following the Catnic/Improver decisions, and as each decision actually represents a different approach to construction, it is the author's belief that it is important that the distinction between the Diplock/Hoffmann approach be recognised, and that the current confused position be remedied by the House of Lords at the earliest opportunity.
Arnander Irvine & Zietman
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