Re Gang-Nail Australia Ltd v Multinail Truss Systems Pty Ltd and Hydro-Air Australia Pty Ltd [1991] FCA 579; 738 Patent 23 IPR 73 (28 November 1991)

FEDERAL COURT OF AUSTRALIA

Re: GANG-NAIL AUSTRALIA LTD
And: MULTINAIL TRUSS SYSTEMS PTY LTD and HYDRO-AIR AUSTRALIA PTY LTD
No. V G305 of 1989
FED No. 738
Patent
23 IPR 73

COURT

IN THE FEDERAL COURT OF AUSTRALIA
VICTORIA DISTRICT REGISTRY
GENERAL DIVISION
Olney J.(1)

CATCHWORDS

Patent - infringement action - construction of licence agreement - implied term - construction of claim in patent specification - identifying essential integers of claim.

Patents Act 1952

Shirlaw v Southern Foundaries (1926) Ltd (1939) 2 KB 206

Codelfa Construction Pty Ltd v State Rail Authority of NSW [1982] HCA 24; (1982) 149 CLR 337

BP Refinery (Westernport) Pty Ltd v Shire of Hastings (1978) 52 ALJR 20

Con-Stan Industries of Australia Pty Ltd v Norwich Winterthur Insurance (Australia) Ltd [1986] HCA 14; (1985-6) 160 CLR 226

Decor Corporation Pty Ltd and anor v Dart Industries Inc. (1988) 13 IPR 385

Populin and anor v H.B. Nominees Pty Ltd [1982] FCA 45; (1981) 59 FLR 37

Catnic Components Ltd and anor v Hill and Smith Ltd (1982) RPC 183

Commonwealth Industrial Gases Ltd v M.W.A. Holdings Pty Ltd and ors [1970] HCA 38; (1970) 44 ALJR 385

Rhone-Poulenc Agrochimie SA and anor v UIM Chemical Services Pty Ltd and anor (1986) 6 IPR 607

Clarke v Adie (1875) 10 Ch App 667

Clarke v Adie (1877) LR 2 App Case 315

Minnesota Mining and Manufacturing Co. v Beiersdorf (Aust.) Ltd [1980] HCA 9; (1980) 144 CLR 253

Olin Corporation v Super Cartridge Co. Pty Ltd [1977] HCA 23; (1977) 14 ALR 149

HEARING

MELBOURNE
28:11:1991

Counsel for the applicant : Mr D. Shavin

Solicitors for the applicant : Darvall McCutcheon

Counsel for the respondents : Mr B.N. Caine

Solicitors for the rsepondents: Hall and Wilcox (Melbourne) as agents

for Lane and Lane (Sydney)

DECISION

The applicant seeks relief by way of injunction and damages arising out of alleged infringements by the respondents of the Australian Letters Patent. The respondents originally cross-claimed alleging the patent to be invalid but during the course of the trial abandoned the cross-claim and judgment was given thereon for the applicant with costs.

2. On 25 February 1991 Jenkinson J ordered that the question of liability be determined before and separately from any question of quantum of damages.

3. At the trial of the proceedings on 9 to 11 September 1991 two issues fell for determination. First, whether upon the proper construction of a licence agreement made between the second respondent and a predecessor in title of the applicant, the respondents infringed the patent by selling existing stocks of the patented product after the termination of the licence, and second, whether the manufacture and sale by the respondents of another product infringed the patent.

4. The following facts are common cause. Australian Letters Patent No. 491,750 were sealed pursuant to the Patents Act 1952 as of 31 December 1975. The priority date is 16 January 1975. The patent was granted for a term of 16 years commencing on 31 December 1975 and relates to an invention described as a connector plate (referred to in the proceedings and hereafter in these reasons as the PT plate). The applicant became registered as the proprietor of the patent on 19 June 1989. By agreement dated 1 May 1984 (the licence) the then registered proprietor of the patent granted the second respondent a licence to manufacture and sell the PT plate in Australia. The licence terminated on 30 April 1989. At that date the second respondent held stocks of the PT plate which were manufactured by it pursuant to the licence and either or both of the respondents has or have since sold some or all of those stocks. Since early in 1989 the respondents have manufactured and sold in Australia 2 types of connector plates (referred to in the proceedings and hereafter in these reasons as the P plate and the MN plate) which are of similar (although not identical) design to the PT plate. For practical purposes the P plate and the MN plate are accepted as not being significantly different from one another.

5. The issues which require determination at this stage of the proceedings are whether the respondents have infringed the patent by reason of first, the sale of the existing stocks of PT plates since 30 April 1989 and second, the manufacture and sale of P and MN plates.
The Licence Agreement

6. The respondents concede that there is no express term of the licence which deals with the sale or disposal after the expiration of the licence of plates which have been lawfully manufactured during the licence period. It is said, however, that the respondents rely upon an implied term of the licence in justification.

7. The principles relating to the implying of terms into a contract are well established. Counsel for the respondents referred to decisions in Shirlaw v Southern Foundaries (1926) Limited (1939) 2 KB 206; Codelfa Construction Pty Ltd v State Rail Authority of NSW [1982] HCA 24; (1982) 149 CLR 337; BP Refinery (Westernport) Pty Ltd v Shire of Hastings (1978) 52 ALJR 20; and Con-Stan Industries of Australia Pty Ltd v Norwich Winterthur Insurance (Australia) Ltd [1986] HCA 14; (1985-6) 160 CLR 226. The five principles arising from these authorities which counsel sought to address are that the term sought to be implied must first, be reasonable and equitable, second, be so obvious that it goes without saying, third, be capable of clear expression, fourth not contradict any express term of the contract and last, be necessary to give business efficacy to the contract.

8. The case for the respondents was put thus. The object of the licence was to permit the licensee to engage in conduct which would otherwise be unlawful. It is reasonable to infer that the parties contemplated that plates would be manufactured in bulk from time to time and that at any one time there would be on hand stocks in excess of orders. To require the licensee to fine tune its production so that at the end of the term of the licence it would not have stock on hand would be to fly in the face of commercial commonsense. These considerations are said to satisfy the relevant principles relating to implied terms.

9. Whilst it was not suggested by counsel for the applicant that the licence contained any express term that would be contradicted by an implied term authorising the sale of the patented product after the termination of the licence, the provisions of paragraph 12, which are quoted below, seem to me to address the issue in precise terms:

12. NON-COMPETITION.
During the continuance of this Agreement, LICENSEE shall not
manufacture, market or sell any products that may in any way compete
with the Licensed Products or with the Imported Products. In the
event of termination or cancellation of this Agreement for any reason
or cause, LICENSEE shall not, directly or indirectly, enter into the
production, manufacture, marketing or sale of any product of
LICENSOR, including but not limited to the products licensed herein,
or products similar to or competitive therewith for a period of
three(3) years from the date of such termination or cancellation.

10. Subject to a provision for immediate termination for cause, the licence was for an initial term of 5 years with automatic renewals for successive terms of 3 years each unless and until either party should give at least 30 days prior written notice to the other party of its intention not to renew at the expiration of the then current term. (Although no evidence was given as to the circumstances, it is common cause that the licence terminated at the end of the initial 5 year term.) Such a provision seems to me to have clearly addressed most of the questions raised in the respondents' submissions. The licensee was to have a secure tenure of the right to manufacture and sell the product unless and until notice of intention be given in accordance with the agreement. That was the agreement and it was a reasonable agreement and capable of being given effect to. Had the agreement not provided for an agreed period of notice of non-renewal the contrary conclusion may well have been open, but that is not the case. Nor is it so obvious as to go without saying what other term or terms should be implied. It is not obvious that the licensee should have the right to continue to sell off its stock of the product for an unlimited period after termination of the agreement.

11. There is no basis in law for implying any term in the licence which would authorise the sale of PT plates after the termination of the licence on 30 April 1989. It is appropriate therefore that I should order an inquiry as to damages or an account. As the patent has still a short time to run I will restrain the respondents from promoting, offering for sale, supplying or selling the PT plate until the expiry of its term.
The P and MN Plates

12. The applicant's case is that by manufacturing and selling the P plate and the MN plate the respondents have infringed the patent. As indicated above there is for present purposes no significant difference between the P plate and the MN plate and accordingly in the evidence at trial and in these reasons, reference to the MN plate has been taken to include reference to the P plate.

13. The patent specification describes the PT plate as follows:

A connector or nailing plate having a plurality of openings
arranged in columns extending lengthwise of the plate, the
openings in each column being spaced at equal intervals and
the columns being spaced at equal intervals transversely of
the plate. Each opening has a tooth struck from each end
thereof with the lateral planes of the teeth of certain
openings being skewed relative to the longitudinal axis of
their respective columns at a first skew angle and with the
lateral planes of the teeth for certain other openings being
skewed at a second skew angle substantially equal in
magnitude but opposite in direction to the first skew angle.

14. The specification summarises the invention (in part) in these terms:

Among the several objects of the present invention may be
noted the provision of a connector or nailing plate which
may readily be imbedded in wood members either by a fluid
operated press or by a gantry roller press; the provision of
such a connector plate which readily penetrates commercially
available lumber without bending of the teeth; the provision
of such a connector plate which resists rotation relative to
the wood members when subjected to both axial, nonaxial and
torsional loading; the provision of such a connector plate
in which its teeth present a relatively more uniform area to
the wood when nonaxial loads are applied to the wood
members; the provision of such a connector plate having
teeth with high resistance to withdrawal from the wood; and
the provision of such a connector plate which may be readily
and economically fabricated on conventional equipment.

15. The claims defining the invention contain 7 paragraphs but only the first is relevant. The claim is as follows:

1. A connector for securing together adjacent wood
members of a wood structure comprising a plate of mild
commercial steel or the like having a plurality of elongate
openings arranged in columns extending longitudinally of the
plate, each said opening having elongate struck-out portions
of the plate extending generally perpendicular to one face
of the plate at each end of the opening, the struck-out
portions constituting elongate teeth, said openings in each
said column being spaced at substantially equal intervals
relative to one another in the direction of the column and
said columns being spaced transversely across the plate at
substantially equal intervals, each said tooth having a
shank portion and a pointed tip portion terminating at the
free end of the tooth and being generally channel-shapped in
cross section with the side edges of the shank portion being
substantially parallel, both teeth of certain openings being
so oriented relative to the longitudinal axes of their
respective columns that vertical planes tangent to portions
of the side edges of these latter teeth are skewed at a
second predetermined angle substantially equal in magnitude
but opposite in direction to said first predetermined angle,
each said tooth being a substantial duplicate of the tooth
at the opposite end of its respective opening with both
teeth in one opening being skewed at the same angle and in
the same direction.

16. In opening, counsel for the applicant helpfully canvassed the leading authorities relevant to what he said were the two issues to be addressed, namely, the proper method of construing a claim and the test for infringement. The authorities referred to were Decor Corporation Pty Ltd and another v Dart Industries Inc. (1988) 13 IPR 385; Populin and another v H.B. Nominees Pty Ltd [1982] FCA 45; (1981) 59 FLR 37; Catnic Components Ltd and another v Hill and Smith Ltd (1982) RPC 183; and Commonwealth Industrial Gases Ltd v M.W.A. Holdings Pty Ltd and others [1970] HCA 38; (1970) 44 ALJR 385. In addition, counsel for the respondents referred to Rhone-Poulenc Agrochimie SA and another v UIM Chemical Services Pty Ltd and another (1986) 6 IPR 607.

17. In Rhone-Poulenc (a decision of the Full Court) Lockhart J addressed the principles relating to the two issues referred to by counsel at pp 620-1 thus:

In an action to restrain the infringement of a patent it is
first necessary to construe the claims in the specification
which define the invention. It is, I think, permissible to
have regard to the language of the specification as a whole
when construing the claims but it must be remembered that
the invention the subject of a valid patent is defined
solely by the claims in the specification. A complete
specification under the Patents Act 1952 must end with a
claim or claims defining the invention: s.40(1)(b).
.....
To establish infringement of combination patent claims such
as these the patentee must show that the alleged infringer
has taken each and every one of the essential integers of
the claims: see Populin v HB Nominees Pty Ltd [1982] FCA 45; (1982) 41 ALR
471; Terrell on The Law of Patents, 13th ed, 1982, para.6-51.
.....
However, it is well established that the extent to which
recourse may be had to the language of the general body of
the specification in order to construe the claims in the
specification is limited. I respectfully adopt the words of
Lord Russell of Killowen in Electric and Musical Industries
Ltd v Lissen Ltd (1939) 56 RPC 23 at 39: "The claims must
undoubtedly be read as part of the entire document and not
as a separate document; but the forbidden field must be
found in the language of the claims and not elsewhere. It
is not permissible, in my opinion, by reference to some
language used in the earlier part of the specification to
change a claim which by its own language is a claim for one
subject-matter into a claim for another and a different
subject-matter, which is what you do when you alter the
boundaries of the forbidden territory."
The specification and the claims must be construed through
the eyes and minds of those skilled in the art at the
material time, namely, the priority date: Codex Corp v
Racal-Milgo Ltd (1983) RPC 369 per May L.J. at 381. It must
also be borne in mind that decisions regarding the matters
to be included in the claims in a patent rest exclusively
with the patentee. In Walker v Alemite Corporation [1933] HCA 39; (1933)
49 CLR 643 at 656, Dixon J quoted with approval the dictum
of Lord Parker in Fellows v Thomas William Lench Ltd (1916)
34 RPC 45 at 55: "A claiming clause operates as a disclaimer
of what is not specifically claimed, and for such disclaimer
there may be reasons known to the inventor but not to the
court."

18. (Although in the foregoing Lockhart J specifically refers to the infringement of a combination patent, it has not been suggested that the same comments are not valid in respect of any infringement action.)

19. In Decor (which is the most recent of the authorities cited) Lockhart J was again a member of the Full Court and at p 391 of the report he made a number of comments to the same effect as those quoted above. In the same case Sheppard J, after a detailed analysis of the authorities summarised (at p 400) "the relevant rules of construction which may be distilled from the authorities referred to above." His Honour then set out the following 10 "rules":

(1) The claims define the invention which is the subject
of the patent. These must be construed according to their
terms upon ordinary principles. Any purely verbal or
grammatical question that can be answered according to
ordinary rules for the construction of written documents is
to be resolved accordingly.
(2) It is not legitimate to confine the scope of the
claims by reference to limitations which may be found in the
body of the specification but are not expressly or by proper
inference reproduced in the claims themselves. To put it
another way, it is not legitimate to narrow or expand the
boundaries of monopoly as fixed by the words of a claim by
adding to those words glosses drawn from other parts of the
specification.
(3) Nevertheless, in approaching the task of construction,
one must read the specification as a whole.
(4) In some cases the meaning of the words used in the
claims may be qualified or defined by what is said in the
body of the specification.
(5) If a claim be clear, it is not to be made obscure
because obscurities can be found in particular sentences in
other parts of the document. But if an expression is not
clear or is ambiguous, it is permissible to resort to the
body of the specification to define or clarify the meaning
of words used in the claim.
(6) A patent specification should be given a purposive
construction rather than a purely literal one.
(7) In construing the specification, the court is not
construing a written instrument operating inter partes, but
a public instrument which must define a monopoly in such a
way that it is not reasonably capable of being misunderstood.
(8) The body, apart from the preamble, is there to
instruct those skilled in the art concerned in the carrying
out of the invention; provided it is comprehensible to, and
does not mislead, a skilled reader, the language used is
seldom of importance.
(9) Nevertheless, the claims, since they define the
monopoly, will be scrutinised with as much care as is used
in construing other documents defining a legal right.
(10) If it is impossible to ascertain what the invention is from a
fair reading of the specification as a whole, it will be invalid.
But the specification must be construed in the light of the common
knowledge in the art before the priority date.

20. I propose to apply the various principles enunciated in the foregoing extracts from the judgments of Lockhart and Sheppard JJ to the facts of the instant case for the purpose of resolving the matters presently in issue between the parties.

21. The evidence at trial consisted of the affidavits of the parties' expert witnesses, namely, Edward Peter Lhuede (for the applicant) and Yash Pal Bhasin (respondent) both of whom were called for cross-examination. In addition a number of documents relating to the patent, the specification and the licence were tendered by consent as were several samples of what was agreed to be the 'prior art'.

22. In his affidavit, at paragraph 9, Dr Bhasin has 'rewritten' claim 1 of the patent in a form which identifies the several integers of the claim in a helpful manner which I reproduce below:

(i) Plurality of elongate openings.
(ii) Arranged in columns extending longitudinally of the plate.
(iii) Each said opening having elongate struck-out portions
of the plate.
(iv) Extending generally perpendicular to one face of
the plate at each end of the opening.
(v) The struck-out portions constituting elongate teeth.
(vi) Said openings in each said column being spaced at
substantially equal intervals relative to one
another in the direction of the column.
(vii) Said columns being spaced transversely across the
plate at substantially equal intervals.
(viii) Each tooth having a shank portion.
(ix) And a pointed tip portion terminating at the free
end of the tooth.
(x) And being generally channel shaped in cross section.
(xi) With the side edges of the shank portion being
substantially parallel.
(xii) Both teeth of certain openings being so oriented
relative to the longitudinal axes of their respective
columns that vertical planes tangent to portions of
said teeth side edges toward said certain openings are
skewed in one direction at a first predetermined angle
with respect to said longitudinal axes of their
respective columns.
(xiii) Both of the teeth of certain others of said
openings being so oriented relative to the
longitudinal axes of their respective columns that
vertical planes tangent to portions of the side
edges of these latter teeth are skewed at a second
predetermined angle substantially equal in
magnitude but opposite in direction to said first
predetermined angle.
(xiv) Each tooth being a substantial duplicate of the tooth
at the opposite end of its respective opening.
(xv) With both teeth in one opening being skewed at the
same angle and in the same direction.

23. Samples of the PT, P and MN plates are exhibited to Lhuede's affidavit sworn 8 February 1991. It is common cause that the sample PT plate was manufactured pursuant to the licence, and in the absence of any contrary suggestion, I infer that the sample displays all of the several integers identified in the claim. The applicant's case primarily is that the P plate and the MN plate have taken each and every of those integers, however, if that not be found to be so, it is said that each and every one of the essential integers of the claim has been taken.

24. A casual visual comparison of the PT and MN plates may at first suggest to a lay person that the two are substantially the same but closer examination reveals that whereas the teeth of the PT plate appear to be more or less consistently angled to the longitudinal axes of their respective columns, the teeth of the MN plate have the appearance of having been slightly twisted so that the orientation of the shank or shaft of each tooth to the longitudinal axis of its respective column constantly changes.

25. Although the onus is on the applicant to establish the claimed infringement it will be helpful to commence an examination of the evidence by referring to what the respondents say about the MN plate. In paragraph 23 of his affidavit of 14 June 1991 Dr Bhasin expressed the view, based on measurements (which he described in detail earlier in the affidavit) and his visual observations of the plate, that 4 features claimed in the patent are not present in the MN plate, namely:

(i) the teeth of the MN plate do not have a shank
portion; (Integer (viii))
(ii) the side edges of the teeth of the MN plate are not
straight but curved and therefore cannot properly
be described as substantially parallel; (Integer (xi))
(iii) vertical planes tangent to the portions of certain
openings of the teeth side edges at the base level of
the MN plate toward the opening are not skewed but are
substantially at right angles to the longitudinal axes
of the plate column; (Integer (xii))
(iv) the vertical planes tangent to the portions of the
teeth side edges at the base levels of certain
other openings in the MN plate are substantially
equal in magnitude but not opposite in direction to
the vertical planes referred to in (iii) above.
(Integer (xiii))

26. Dr Bhasin's opinion is to some extent dependent upon his understanding of the words used in the claim and at paragraph 10 of his affidavit he dealt with 3 terms, the understanding of which is fundamental to a proper construction of the claim. The relevant portion of paragraph 10 is as follows:

10. In order to properly undertake a comparison of the
features of the MN plate and the features claimed in
claim 1 it is first necessary to set out my
understanding of various terms used in the patent in suit.
(i) Shank Portion
I understand the term "shank portion" referred to in
claim 1 to mean that portion of the tooth which
extends vertically upwards from the plate commencing
at the base and terminating at the region where the
side edge changes its angle and becomes the tip
portion. I also understand the edges of the shank
portion as claimed must be straight.
(ii) Side edges of the shank portion
being substantially parallel
The straight side edges of the shank portion are
formed in alignment with the sides of the slot or
opening and are therefore substantially parallel.
(iii) Skewed
In the context of the claims of the patent in suit I
understand the term "skewed" to refer to the fact that
the pair of teeth of a given slot are turned or
rotated at their root through an angle other than a
substantially right angle relative to the longitudinal
axis of that slot.

27. The witness's understanding expressed in the foregoing was the subject of considerable cross-examination, but in the context in which the terms are used there is in my view little scope for debate. The 'struck-out portions constituting elongate teeth' (integer (v)) are said to each have 'a shank portion' (integer (viii)) and 'a pointed tip portion terminating at the free end of the tooth' (integer (ix)). The 'shank portion' of each tooth is clearly that part which is not 'the pointed tip portion'. On my understanding of the words used, it is not the case that the teeth of the MN plate do not have a shank portion. I do not think that it necessarily follows, as Dr Bhasin would have it, that the edges of the shank portion as claimed must be straight, however, such a conclusion may follow from the requirement of integer (xi) that the side edges of the shank be substantially parallel in which case the side edges may be merely substantially straight. The term 'skewed' is one capable of having a variety of meanings depending upon the context in which it is used but it seems to me that in the context of the claim in this patent, when used in combinations such as 'skewed in one direction at a first predetermined angle' and 'skewed at a second predetermined angle substantially equal in magnitude but opposite in direction to said first predetermined angle' there is no scope for attributing a meaning other than slanted or at an angle other than a right angle.

28. Both Mr Lhuede and Dr Bhasin possess relevant, although essentially different, qualifications to justify them giving opinion evidence relating to the respective features of the PT and MN plates, and to comment on the features of each plate in relation to the claim in the patent specification. Although each carried out a series of tests for the purpose of identifying the essential features of the plates, their methodology was different as were their conclusions.

29. The nature of the patented product and the method of its manufacture are such that meaningful measurement is difficult to achieve. The plates are made of relatively thin steel and the teeth are simply struck out with a punch. The result is that neither the size, shape nor orientation of the teeth is entirely consistent. In particular, the edges tend to be quite rough. These comments apply equally to the PT and the MN plates. In the result I have found that the expert evidence has not helped me a great deal and that it provides little more assistance than can be obtained by visual examination. Having said this I set out below my findings:

(1) In relation to the PT plate:
(a) the shanks of the teeth are skewed with respect to the
longitudinal axes of their respective columns;
(b) the shanks of the teeth in each alternate column are skewed
at substantially the same angle;
(c) the shanks of the teeth in each other column are skewed at
an angle substantially equal in magnitude but opposite in
direction to the first mentioned teeth;
(d) the sides of the shank of the teeth are substantially
parallel;
whereas
(2) in relation to the MN plate:
(a) at the base of the shank, the teeth are substantially at
right angles to the longitudinal axes of their respective
columns;
(b) the shanks are twisted more or less uniformly so that at
their upper extremity the shanks are skewed with respect to
the longitudinal axes of their respective columns;
(c) the shanks of teeth in each alternate column are twisted to
substantially the same extent;
(d) the shanks of teeth in each other column are twisted to
substantially the same extent but in the opposite direction
to the first mentioned teeth;
(e) the sides of the shanks of the teeth are substantially
parallel to each other in the sense that the shank of each
tooth is of more or less constant width from the base of the
tooth to the commencement of the tip portion.

30. The conclusion which follows from the foregoing findings is that the MN plate differs from the PT plate in so far as the teeth of the MN plate are not skewed in the manner described in integers (xii) and (xiii). It can, therefore, be said that the respondents have not adopted each and every one of the integers identified in the claim. The question remains, however, as to whether the orientation of the teeth relative to the longitudinal axes of the respective columns at either a first predetermined angle or a second predetermined angle substantially equal in magnitude but opposite in direction to the first predetermined angle are essential integers of the claim.

31. In order to identify the essential integers of the claim, the substance of the invention must be understood and borne in mind. The classic statement in this context is in Clarke v Adie (1875) 10 Ch App 667 where James L.J. said at p 675:

... the patent is in the entire combination, but there is, or may be,
an essence or substance of the invention underlying the mere accident
of form; and that invention, like every other invention, may be
pirated by a theft in a disguised or mutilated form, and it would be
in every case a question of fact whether the alleged piracy is the
same in substance and effect or is a substantially new or different
combination.

32. In the same case, on appeal to the House of Lords (reported at (1877) LR 2 App Case 315 at p 320) Lord Cairns said that an infringer who took some steps only of the combination might be held "to have taken in substance the pith and marrow of the invention".

33. More than a century later in Minnesota Mining and Manufacturing Co. v Beiersdorf (Aust.) Ltd [1980] HCA 9; (1980) 144 CLR 253, Aickin J (with whom the rest of the High Court agreed) said at p 286:

... it remains the law that a defendant may not take the
substance of an invention unless the wording of the claims
makes it clear that the relevant area has been deliberately
left outside the claim.

34. The so called "pith and marrow" test is however merely an aid in construing the claim contained in the patent specification and it remains the law that infringement will occur only when each essential integer is taken. Thus in Olin Corporation v Super Cartridge Co. Pty Ltd [1977] HCA 23; (1977) 14 ALR 149 at p 159 Gibbs J (as he then was) said:

... the principle that there may be infringement by taking
the "pith and marrow" or the substance of an invention does
not mean that there will be an infringement where the
patentee has by the form of his claim left open that which
the alleged infringer has done. And it does not affect the
fundamental rule that there will be no infringement unless
the alleged infringer has taken all of the essential
features or integers of the patentee's claim: see Rodi and
Weinenbirger AG c Henry Showell Ltd (1969) RPC 367,
especially at 383-4.

35. Without resorting to the body of the specification for guidance in the construction of the claim, the words used in the claim, notably "skewed in one direction at a predetermined angle" and "skewed at a second predetermined angle substantially equal in magnitude but opposite in direction to the first said predetermined angle" are capable of being understood according to ordinary rules for the construction of written documents. According to the ordinary meaning of the words used, the teeth are to be skewed relative to the longitudinal axes of their respective columns at either one angle or the other, and the latter is to be substantially equal in magnitude but opposite in direction to the former. The use of the descriptive words "a first predetermined angle" and "a second predetermined angle" and the fixed relationship between the two angles indicates an intention to state with precision the orientation of the teeth. The angle of orientation is, in terms of the claim, to be measured by the relationship of the longitudinal axes of the respective columns to "vertical planes tangent to portions of said teeth side edges". Given that teeth are to be skewed at a predetermined angle, it must necessarily follow that each tooth is skewed at a single angle, which in my opinion does not admit of a construction which would involve the taking of tangent lines at various points on the shank of a tooth and comparing the angle of each tangent line to the relevant longitudinal axis with the angles produced by taking tangent lines at corresponding levels on other teeth. The claim, literally construed, does not extend to a connector plate of this type with teeth that are twisted so that the angle of vertical planes measured at different heights above the base of the teeth are not substantially the same.

36. Although this is not a case in which resort to the specification is warranted to resolve any ambiguity in the claim, as Sheppard J has pointed out in Decor, there may be cases in which the meaning of words used in the claim are qualified or defined by what is said in the body of the specification. Accordingly, I propose to look to the specification to ascertain whether this be the case. However, it is appropriate first to make a brief comment on the prior art, as this is necessary to understand in what follows, reference to conventional plates.

37. Exhibit 7 in the proceedings (which was put in by consent) comprises examples of what is agreed to be the prior art. It consists of 5 metal plates, of which one is obviously quite irrelevant to the proceedings. The remaining 4 are said to have been manufactured by the applicants and are substantially similar to the PT plate except in 2 respects. First, there is only one struck-out portion constituting an elongate tooth for each elongate opening (as distinct from 2 such teeth for each opening as on the PT plate), and second, the lateral planes of the teeth are substantially at right angles to the longitudinal axes of the columns of teeth (as distinct from being skewed as on the PT plate).

38. In the patent specification, the function of the invention is said to be "for securing together adjacent wood members to form a wood structure (e.g. for securing together the web and chord members of a roof or floor truss)". It is also said that when the teeth are imbedded into the wood, the connector plate must be sufficiently strong to hold adjacent wood members securely together so as to withstand the substantial tension, compression, shear and/or torsion loads to which the joint is subjected during fabrication of the structure, transportation of the structure to the building site and erection of the building, and during the life of the building with an adequate margin of safety to accommodate overload conditions. The strength of the connector plate (referred to as the plate rating) is conventionally evaluated by determining the ability of the connector plate teeth to resist withdrawal from the wood member and to resist movement through the wood member when two wood members joined together in end-to-end abutting relation by the connector plates are subjected to axial tension loading. However, in practice, connector plates joining the web and chord members of a truss may have loads other than axial tension loads applied thereo. These non-axial loads may tend to cause the plate to rotate relative to the wood members or to tear or split the wood members thus weakening the joint. Most often the strength and load-holding capacity of the tooth is greatest when the face of the tooth is at right angles to the load. Thus conventional plates have a high load-holding capacity when the load is applied in one direction (e.g. along a line perpendicular to the lateral plane of the teeth of the connector), but may have a substantially lower load-holding capacity when the load is applied in another direction (e.g. along a line substantially parallel to the lateral plane of the teeth). If the load is applied parallel to the lateral plane of the teeth, the teeth present a relatively narrow edge or area to the load and the wood in contact with the narrow edges or faces of the teeth may be subjected to such high loading per unit area that the wood may fail.

39. Among the several objects of the invention summarised in the specification (and quoted earlier in these reasons) are the provision of a connector plate which resists rotation relative to the wood members when subject to both axial, non-axial and torsional loading and the provision of a connector plate in which its teeth present a relatively more uniform area to the wood when non-axial loads are applied to the wood members. These objects are clearly in response to the perceived shortcomings of the prior art and the invention seeks their achievement by the device of causing the elongate teeth to be skewed in the manner described.

40. I can find nothing in the body of the specification to suggest that any relevant term used in the claim is defined in such a manner as to attribute to it a meaning other than its ordinary meaning. However, it is obvious from the specification that the major objectives of the invention are intended to be achieved by the process of skewing the teeth.

41. The language of the claim is precise, unambiguous and appropriate. I am unable to accept that the words "skewed at a predetermined angle" describe other than an essential integer of the invention. In so far as I have found that the teeth of the P and MN plates are not skewed in the manner described in the claim, I am of the view that the respondents have not taken each and every integer of the invention and accordingly have not infringed the applicant's patent by manufacturing and selling the P plate and the MN plate.

42. I propose the following orders to reflect the foregoing conclusions:

1. The respondents' cross-claim be dismissed with costs to be taxed.
2. Declare that the respondents have infringed the applicant's patent
by selling the PT plate after termination of the licence.
3. Order an inquiry as to damages or an account, and for this purpose
the proceeding be adjourned for directions.
4. The respondents be restrained during the term of the patent from
promoting, offering for sale, supplying or selling the PT plate.
5. The application be otherwise dismissed.

43. I will hear counsel on the form of the orders to be made and on the question of costs.