Drilling for the meaning of words: The SCA’s interpretation of patent claims

September 1st, 2017

By Ryan Tucker

Sometimes we, as attorneys, comment on cases where new precedents are set, or new principles espoused, to deal with a set of circumstances not yet faced by the courts. At other times, we report on judgments that reinforce existing law and sets of principles that have even, in some lawyers’ minds, become trite. Such is this case.

The dicta from Dambuza JA in Orica Mining Services SA (Pty) Ltd v Elbroc Mining Products (Pty) Ltd [2017] 2 All SA 796 (SCA), are far from groundbreaking. But they do serve to fortify what patent practitioners understand to be the law in relation to patent construction. Additionally, patent-related cases so rarely reach the Supreme Court of Appeal (SCA) that it is worth commenting on them in this case.

Additionally, what strikes me from the Orica case is the care which patent prosecution attorneys need to take (and all other lawyers, in fact, when drafting any type of document for a client) because in legal proceedings, it can come down to the interpretation of one word (in this case, the word ‘between’) as to whether the client’s claim can stand muster or be dismissed by the courts.

Dambuza JA (for the full Bench) was required to assess the alleged infringement by Elbroc Mining Products (Pty) Ltd of patent number 2001/10382 entitled ‘Portable Drilling Apparatus’ of Orica Mining Services South Africa (Pty) Ltd (the patent). The invention is known in the industry as a ‘roof bolter rig’, which enables mine-hole drilling without having to manually support the machine in position.

In its ‘preferred embodiment’, the invention consists of two extendable telescopic props, onto which, a drill carriage is mounted. The props support the surface of the hanging wall during drilling, reducing the risk of the wall collapsing onto the rig user. Each prop has a pair of cylinders joined at either end by a brace and a base. A hydraulically operated piston slides into each cylinder. The free end of the piston forms a point and a conical stud extends centrally from the outer surface of the base.

Elbroc sold roof bolter rigs that perform an identical function to Orica’s patented roof bolter rig, causing Orica to sue Elbroc for alleged patent infringement of its patent claims, including claim 1, which is reproduced below:

‘1. A portable self-supporting drill rig comprising a pair of spaced apart telescopic props with a carriage between them, the carriage moveable along an axis substantially parallel to those of the props and supporting a drill mounted on the carriage …’ (my italics).

If claim 1 was held by the court to be infringed, so would all the other dependent claims.

In defending the action, Elbroc claimed that the word ‘between’ had to be interpreted as ‘linearly between’ the props. Elbroc’s assertion was that its variant of the invention, not being ‘linearly between’ the two props, allowed its design around to fall outside the claim.

Below are the diagrams of the patent (left) and Elbroc’s drill rig (right).

In the court of the Commissioner of Patents, the court held that because the carriage in Elbroc’s drill rig was offset from the linear space between the props, there had been no infringement of the patent. Mabuse J also held that Orica’s interpretation of the word ‘between’ amounted to an impermissible extension of the meaning of the word, because it sought ‘to include a carriage which is offset at a right angle to the co-linear line between the pair of telescopic props at an undefined and unspecified distance from the space between the two props’. But Orica appealed to the SCA, and persisted in its contention that on a proper construction, the patent claims required only that the drill carriage be located ‘in the space between the two props, even if not in the same linear plane as the props’. Therefore, Elbroc’s argument incorrectly equated the word ‘space’ with the word ‘line’.

Dambuza JA, in contrast to the court a quo, took a ‘contextual’ and ‘purposive’ approach to claim construction, and referred to several supporting judgments, including Multotec Manufacturing (Pty) Ltd v Screenex Wire Weaving Manufacturers (Pty) Ltd 1983 (1) SA 709 (A) at 721 to 722, where the court held:

‘[T]he Court should always guard against too “textual” an approach in the interpretation of claims in a patent specification. It is true that it is in the claims that a patentee stakes out and defines his monopoly; and that the claims must be looked at in order to determine whether an infringement has taken place. But by peering too closely at the language of a claim the Court may overlook an infringement which takes the substance of the invention. …

In this context it is often said that any infringer who takes the “pith and marrow” of the invention commits an infringement even though he omits an unessential part or substitutes for that part a mechanical equivalent. …

Where the alleged infringer has deviated in regard to some feature from the invention as literally claimed in the specification, it may often be a matter of considerable difficulty to determine whether the deviation relates to an essential or a non-essential feature of the relevant claim or claims.’

The SCA added that if the meaning of a claim, properly constructed, is sensible, clear and unambiguous, it cannot be restricted or extended by anything else stated in the body and title of the specification. However, the court went on to state that Elbroc forwarded three different dictionary meanings of the word ‘between’ and that, in selecting ‘linearly between’, (impliedly) Elbroc itself was not clear about the meaning of the word.

The court went on to state that the dictionary meaning (a purely literal interpretation) of the word is only a guide and the appropriate question is: What is the meaning applicable in the context of the particular document under consideration (in this case, the patent document as a whole)? The SCA held that the definition ‘with something on each side’ was the most sensible.

The SCA then turned to discuss purposive interpretation, stating that within the context of patent construction, the purposive approach takes into account the practical knowledge and experience of the ‘person skilled in the art’. It considers that such a person would understand whether strict compliance with a particular word or phrase was intended, and whether a variant of the word would have an effect on the way the invention works, such that the impugned object would fall outside of the monopoly protected in the claims, and there would therefore be no infringement.

In conclusion, Dambuza JA held that Elbroc’s argument could not be sustained:

‘Purposive interpretation is not an undue extension of the language of patent claims. In my view to interpret the word “between” as meaning linearly between the props is not in accordance with a purposive interpretation of the specification, as delineated by the claims. The advantage of the invention is that the telescopic props give support not only to the hanging roof of the stope, but also to the drill located “between” them, so that it may be operated remotely. This is precisely what the respondent’s drill rig seeks to achieve.’

The SCA has now clearly entrenched in our law that the proper mode of construction of patent claims is a contextual and purposive one (if this was not clear already). Not only should one look to the rest of the patent document when interpreting claims, but also these should be interpreted with the skilled person in mind, and what he or she would see as the meaning of the word(s).

To those disappointed by the outcome of the SCA judgment – those who may feel that a purely literal interpretation should always be used instead of the contextual and purposive interpretation – my view is this: Do not assume that such purposive interpretation provides increased patent protection than would a purely literal one.

Although, usually, a purposive interpretation may lead to claims being read more broadly and to the benefit of the patentee, such constructive style need not do so. All that the contextual and purposive styles require are that –

  • the claims should not be looked at in isolation;
  • the rest of the patent document should be included in the interpretative exercise; and
  • they should be interpreted through the lenses of the ‘person skilled in the art’, taking cognisance of the purpose and function of the invention.

How broadly such claims will be interpreted depends on the facts and circumstances of each case, and how the skilled person views –

  • the claims;
  • the purpose and function of the invention; and
  • the way the claims are drafted.

This is why it is so important to have an experienced patent attorney draft patent claims and specifications.

I do not believe that a literal interpretation should be completely excised from our law on the interpretation of patent claims (although a purely literal interpretation should be). There may be good reasons why a person skilled in the art would read a patent claim more restrictively; using the literal meaning of the words. These include cases where the patent document includes words that are to be strictly understood, to avoid some closely related piece of prior art, which may anticipate the patent if construed broadly.

Also, where the ‘person skilled in the art’ would view the choice of words as deliberate, particularly in using technical terms and specific numerical limitations (see R Tucker ‘Patent claim construction: Numerical limitations’ 2016 (Dec) DR 34), this may reduce the scope of the patent claims. As a result, a literal interpretation of certain terms and numerical limitations is used as part of the purposive approach to interpretation, where such is in line with what the skilled person would understand the claims to mean.

In my view, Dambuza JA saw through Elbroc’s limited, strict and literal interpretation of the word ‘between’ as meaning ‘linearly between’. He decided not to play ‘dictionary word games’ with Elbroc, and simply utilised the contextual and purposive approaches to arrive at his decision. For me, this was a pragmatic and commonsensical way of seeing the meaning of the words contained in the claim (as exemplified by his interpretation of the word ‘between’ meaning ‘with something on each side’).

Dambuza JA cut through the analysis provided in evidence given by the expert witnesses of and arguments of counsel for both parties, as to what the skilled person would understand by the word ‘between’, and dealt sensibly and clearly with the facts and issues in the case (which there is ample precedent for in patent cases – the judge is the ultimate arbiter). His judgment highlights that the contextual and purposive styles are at the apex of the interpretative exercise, and that other principles act merely as guides to assist the court in determining the construction of patent claims.

Ryan Tucker BSc Genetics and Developmental Biology & Microbiology and Biotechnology LLB (Wits) is an attorney at RM Tucker attorneys in Johannesburg.

This article was first published in De Rebus in 2017 (Sep) DR 26.