THE SUPREME COURT OF APPEAL
OF SOUTH AFRICA
CASE NUMBER: 162/97
In the matter between:
NAMPAK PRODUCTS LIMITED
First Appellant
H L & H TIMBER PRODUCTS (PTY)
LIMITED
Second Appellant
and
MAN-DIRK (PTY) LIMITED
Respondent
CORAM:
VIVIER,
HOWIE,
SCHUTZ,
PLEWMAN JJA and MELUNSKY AJA
DATE OF HEARING:
5 MARCH 1999
DATE OF JUDGMENT:   26 MARCH 1999
Patent infringement - Construction of claims - Purposive
construction - Caution in regard to the adoption of the test in
Catnic v Hill.
JUDGMENT

PLEWMAN JA
This is an appeal against an order by Roux J, sitting as
Commissioner of Patents, in a matter concerning an alleged
infringement of a patent.  The appellants are the registered joint
proprietors of South African Letters Patent No 90/2427 in respect of an
invention entitled “Pressure Resistant Bag”.  They acquired this by an
assignment from the original patentees.  The respondent manufactures
and sells a competing product.  Appellants applied in the court a quo
on notice of motion for a permanent interdict restraining the respondent
from selling or offering its product for sale and for an order for the
delivery up of any infringing bags.  The Commissioner dismissed the
application with costs but granted leave to appeal to this Court.
The patent was granted with effect from 27 February 1991.  It
was applied for by appellants’ predecessors in title in March 1990,
claiming priority from three prior patent applications.  It seems,
however, that the respondent, too, had been active in the field for some
years.  The affidavits filed in support of the notice of motion are of a
somewhat perfunctory nature.  This may have had an influence on the
response thereto by the respondent.  There was (unusually for patent
litigation) no challenge to the validity of the patent.  In the result there
is on the record no evidence in which the prior art is discussed in any
depth.  Perhaps more importantly, there is not any evidence to show
that the patent, when viewed through the eyes of the skilled addressee,
should be read in any manner which would give the words of the claims
a meaning other than their primary meaning.  This is an aspect to which
I shall return.
In its commercial embodiment the patent takes the form of a bag

used in the support systems employed underground in mines.  Mine
support bags are fitted in or into packs of timber support in excavated
stopes or other underground working places.  The bags are filled under
pressure to wedge the timber supports into position.  There are two
systems in use.  In one system (known as the “weeping system”) the
bag is of a porous woven material and is filled with grout.  The water
in the grout passes through the bag while the solids remain behind and
set to provide solid support.  In the other system (the “non-weeping
system”) the bag is impervious to liquid and a chemically reactive mix
is pumped into the bag which hardens by chemical action to provide the
support.
The specification is (fortunately) not a technically complex
document.  The general description of the invention in the specification
reads:
“This invention relates to a flexible bag which is resistant
to damage from high internal pressure such as would be
caused by filling the bag to a high pressure with a liquid,
grout or the like and to damage caused by loads and/or
shock loads imposed on the outside of the bag when the
bag is filled with air or liquid under pressure.”
The consistory clause reads:
“A pressure resistant bag according to the invention
includes a first bag which is made from an air impervious
plastics material, an envelope which is made from a
reinforced flexible material and in which the first bag is
located, a second bag which is made from reinforced
flexible material in which the envelope is located and a
filler arrangement which is attached to the first bag and
passes through apertures in the envelope and second bag.
Conveniently, the first bag is made from an unseamed

tube of plastics material with the ends of the tube sealed
to provide a closed bag.
Further according to the invention the envelope is in the
form of an open ended tube in which the first bag is
located.  Preferably, however, the envelope is made from
a woven plastics material with the weft threads of the
weave conveniently being circumferential in the tube and
of a higher tensile strength than the warp threads.
In the preferred form of the invention the sealed ends of
the first bag are transverse to the tube axis of the envelope
and are located on the inside of and adjacent the open
ends of the envelope with the end portions of the envelope
together with the sealed end portions of the first bag being
folded back on to an outer surface of the tube with the
first bag and envelope being so located in the second
bag.”
In infringement proceedings one is concerned only with the
invention claimed.  The patent has twenty claims but what is in dispute
between the parties can be dealt with having regard only to the main
claim.  Indeed, only one integer is in dispute and in that regard it is, in
the main, the bearing one phrase has on the construction of that claim
that must be debated.  The claim may, for convenience, be set out as
having the following integers:
“(i)
A pressure resistant bag including
(ii)
A first bag which is made from an air impervious
plastics material
(iii)
An envelope which is made from a reinforced
flexible material and in which the first bag is
located
(iv)
A second bag which is made from a reinforced

flexible material in which the envelope is located
and
(v)
A filler arrangement which is attached to and opens
into the first bag and passes through apertures in
the envelope and second bag.”
It is integer (iv) that gives rise to the debate.
The respondent’s product is very similar to the patented product.
It is stated in the answering affidavits that respondent was engaged in
1989 in development work on, initially, weeping bags but later also on
non-weeping bags.  Tests conducted by it established that the pressures
applied to the non-weeping bags were of such an order that the bags
were unable to withstand the loading.  They required some form of
transverse securement.  What respondent’s witness says is that
respondent then attempted to provide this securement by putting the
bag into a restraining sleeve.  It was found that the bag when so
reinforced worked well and the sleeve assisted in restraining the
tendency of the folded over flaps of the bag to pull away and open the
bag up.  This had been a major problem.  What respondent
manufactured at relevant times was a bag reinforced in this manner -
that is by the  addition of a restraining sleeve to provide the necessary
resistance or strength.  It is common cause that respondent’s bag
exhibits the features of all the integers of the main claim - other than
integer (iv). It is asserted by respondent that its bag avoids the extra
material and labour required to form a second full bag around the
composite inner bag as in the patent.  It therefore does not contain
integer (iv) and, accordingly, does not infringe.

The first task of the court is to construe the claim.  When the
meaning of the claim has been determined the alleged infringing article
is to be compared therewith.  What must be shown is that all of the
features or limitations of the claim are present.  Appellants’ contention
is that respondent’s bag consists of a “bladder” of an impervious plastic
material (which is said to constitute the first bag of the claim), a
“casing” (which is said to constitute the envelope of the claim) and a
“sheath” (which is said to “correspond”to the second bag).  The case
then turns on a short point of construction namely whether the sleeve
of respondent’s bag is a second bag, as that expression is used in the
claims of the patent.
The correct approach to the interpretation of a patent
specification is a topic adverted to in almost every reported decision in
patent law.  But one need go no further than the careful examination of
the problem in Gentiruco A G v Firestone SA (Pty) Ltd 1972 (1) SA
589 (A) at 613D-618G.  Appellants’ counsel, however, sought to
invoke as an aid to the interpretation of the claim the principle known
as “purposive construction”.  For this reason a brief word must be said
with regard to that proposition.  The epithet laden term “purposive
construction” derives from Lord Diplock’s speech in Catnic
Components Limited and Another v Hill and Smith Limited [1982]
RPC 183 (H.L.).    It has been invoked in this Court in the field of
patent law inter alia in Multotec Manufacturing (Pty) Ltd v  Screenex
Wire Weaving Manufacturers (Pty) Ltd 1983 (1) SA 709 (A); Selas
Corporation of America v Electric Furnace Co 1983  (1) SA 1043 (A);
Stauffer Chemical Co & Another v Safsan Marketing and Distribution
Co (Pty) Ltd and Others 1987 (2) SA 331 (A) and Sappi Fine Papers

(Pty) Ltd v ICI Canada Inc 1992 (3) SA 306 (A).  The concept of a
purposive construction was used as an interpretive aid in these cases in
different ways.  In some it is employed as a phrase of general
application in the construction of claims connoting an approach based
upon the skilled addressee’s knowledge of the art (as opposed to a
purely verbal analysis).  In others (as for example in the Multotec case,
supra) it is invoked as an interpretive aid where the alleged infringer
was considered to have appropriated what has been called the “pith and
marrow” of the invention and merely substituted a mechanical
equivalent for an inessential part.  There is in fact no room for its
application in the present case but it is necessary to point out that in all
of the above cases the Court was concerned to establish whether the
particular features of the claimed invention taken by the alleged
infringer represented all the essential features of the claim.  This, in the
final analysis, remains a pure question of construction. In the Catnic
case Lord Diplock, after noting that a patent specification is “a
unilateral statement by a patentee in words of his own choosing”
addressed to persons skilled in the art went on to say (at 243):
“A patent specification should be given a purposive
construction rather than a purely literal one derived from
applying to it the kind of meticulous verbal analysis in
which lawyers are too often tempted by their training to
indulge.  The question in each case is: whether persons
with practical knowledge and experience of the kind of
work in which the invention was intended to be used,
would understand that strict compliance with a particular
descriptive word or phrase appearing in a claim 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 the invention worked.”
How this proposal is implemented is discussed below.  What should
first be noted is that in the Catnic case too the ultimate question was
one of construction.  This is explained in a careful analysis of Lord
Diplock’s test (in the Catnic case) by Hoffman J in Improver
Corporation and Others v Remington Consumer Products Limited and
Others FSR [1990] 181.  At p 189 the learned judge stated:
“In the end, therefore, the question is always whether the
alleged infringement is covered by the language of the
claim.  This, I think, is what Lord Diplock meant in
Catnic when he said that there was no dichotomy between
‘textual infringement’ and infringement of the ‘pith and
marrow’ of the patent and why I respectfully think that
Fox L.J. put the question with great precision in Anchor
Building Products Ltd. v. Redland Roof Tiles Ltd. when
he said the question was whether the absence of a feature
mentioned in the claim was ‘an immaterial variant which
a person skilled in the trade would have regarded as being
within the ambit of the language”.  (The emphasis is that
of Hoffman J.)
But there is another facet of Lord Diplock’s test to which
attention must be directed.  This is the role of s 125 of the English

Patents Act of 1977 and Article 69 of the European Patent Convention.
The convention was concluded in Munich in 1973.  England has
adhered to it.  Article 69 was an attempt to ensure a measure of
uniformity in the construction of patent specifications within the
European community by stipulating permissible readings of patent
claims (the Protocol).  The reason, in brief, lies in the difference
between the traditional approach to claim interpretation in United
Kingdom and the continental approach which rests largely on the views
of persons skilled in the particular art.  An article by B Sherman in
[1991] 54 Modern Law Review p 499 “Patent Claim Interpretation:
The Impact of the Protocol on Interpretation” is instructive in this
regard.  It seems as if the aim has not been wholly achieved.  What
Hoffmann J’s analysis showed is that Lord Diplock’s proposed test was
influenced by the Protocol.  See Hoffman J in the Improver case,
supra, at p 190 and Southco Inc and Another v Dzus Fastner Europe
Ltd [1990] RPC 587 at p 603 and 604.  Lord Diplock’s proposal is that
the court should ask itself three questions.  Two of these are questions
of fact dependent on extrinsic evidence.  To the extent to which this
could be understood to suggest that extrinsic evidence on interpretation
be led in all cases it would not be in accordance with our law.  It is
contrary to the judgment of this Court in the Gentiruco case.  See the
judgment of  Trollip JA at p 617A-618G.  In the cases in this Court in
which the concept of a purposive construction has been invoked this
has always been in a context which in no way detracted from the firmly
established principles of claim construction.  Generally, evidence on
record for other reasons, such as evidence to explain the art and science
in question to enable the court to view the patent “through the eyes of

the addressee”, allowed the court to adopt a purposive approach.  In
the Multotec case, for example, the claim in question was ambiguous
and the invocation of an aid to interpretation was appropriate.
What I have said has been prompted only by the need to point
out that it is not always open to a court to resort to evidence as an aid
to construction.  None of the South African authorities to which I have
referred (nor indeed the English cases other than the Improver
Corporation case  and the Southco case) have directed attention to the
effect of the Protocol in the Catnic case or to the factual nature of part
of the test.  In most cases a test which necessitates extrinsic evidence
will be inappropriate.  The caution sounded by Trollip JA in the
Gentiruco case at p 613 D-E about the use of English and American
decisions remains valid and apposite.  (I should add that Lord
Diplock’s approach has also been invoked in cases not concerning
patents.  An example is Public Carriers Association and Others v Toll
Road Concessionaries (Pty) Ltd and Others 1990 (1) SA 925 (A) at p
943 C-H - again a case where ambiguity was a problem.  But it is
beyond the scope of this judgment to discuss the application of the
Catnic test in decisions other than patent cases.)  What can be said is
that in patent cases the need for a practical construction is obviously
desirable.  But care is called for in the manner in which recourse may
be had to Lord Diplock’s test.
As I have said, the present case is a good example of
circumstances where it would be singularly inappropriate to attempt to
apply the Catnic procedure.  Counsel sought to do so both in the main
argument and in an alternative argument.  In his main argument he
addressed an argument, without evidence on the point, as to what the

“true” invention was.  In the alternative argument he sought to raise a
“pith and marrow” contention, again without any appropriate evidence
having been adduced.  The present patent in fact involves no technical
complexities and uses no esoteric phraseology.  The words of the claim
are ordinary English words clearly used in their ordinary connotation
and the claim is unambiguous.  There is therefore nothing which would
justify a reference either to phraseology in the body of the specification
or to extrinsic evidence relating to the art.  The claim in issue must
simply be read in its own terms.
No aid to interpretation (going any further than the need to read
the document as a whole) is called for.  In the consistory clause itself
there is discussion of the first bag being made of an unseamed tube
with ends sealed to provide a closed bag.  This statement is followed
by a description of the envelope being in the form of an open ended
tube.  The open ended member is thus accurately described as a tube
in contrast to a bag.  With that background one turns to the claim where
one encounters the word “bag” not only used in its ordinary sense but
also used in juxtaposition to the word envelope.  There is also a
reference to a first bag and a second bag.  The ordinary meaning of the
word bag according to the Shorter Oxford English Dictionary is “a
receptacle of flexible material open only at the top (where it can be
closed)”. The word is unambiguous.  The patentee must therefore be
understood to have intended the limitation to the claim which follows
from the use of the words “second bag” to be given effect to.  The
respondent’s product does not have a second bag and therefore does
not infringe the claim.
The appeal is dismissed with costs including the costs of two

counsel.
PLEWMAN JA
CONCUR:
VIVIER JA)
HOWIE JA)
SCHUTZ JA)
MELUNSKY AJA)
SUMMARY
An appeal against the refusal to grant an interdict in a patent
infringement case.  The test of “a purposive construction” as an aid to
the construction of patent claims considered.  The influence of the
Protocol of the European Patent Convention of 1973 in the application
of a “purposive construction” discussed.  Purposive construction held
to be in appropriate on the facts.  Appeal dismissed.