COURT OF APPEAL (CIVIL DIVISION)
ON APPEAL FROM THE HIGH COURT OF JUSTICE
CHANCERY DIVISION (PATENTS COURT)
The Hon Mr Justice Pumfrey
HC 04 C00114, HC 04 C00689, HC 04 C00690
Strand, London, WC2A 2LL
B e f o r e :
THE RT HON LORD JUSTICE RIX
THE RT HON LORD JUSTICE JACOB
| Halliburton Energy Services Inc
|- and -
|Smith International (North Sea) Limited
Smith International Inc
Smith International Italia SpA
WordWave International Ltd
A Merrill Communications Company
190 Fleet Street, London EC4A 2AG
Tel No: 020 7421 4040 Fax No: 020 7831 8838
Official Shorthand Writers to the Court)
Michael Tappin (instructed by the Treasury Solicitor) for the Comptroller of Patents
The Respondents were not present and were not represented
Crown Copyright ©
Lord Justice Jacob (giving the Judgment of the Court):
The position of the Comptroller
"What we see ourselves as here to do is to help the court - to put the other side of the argument to the extent we think it should be put and to make such criticisms of Halliburton's submissions as we believe appropriate."
The Scientific Adviser
Peripheral findings of invalidity
The law as to sufficiency
" It is a basic principle of patent law that the European patent application shall disclose the invention in a manner sufficiently clear and complete for it to be carried out by a person skilled in the art (Article 83 EPC transposed into section 14 of the 1977 Act). This requirement has long been fundamental. The sufficiency of a specification is a question of fact and necessarily depends upon the nature of the invention and the attributes of the skilled person. There is no general rule, and although statements like 'you may not set a man a problem and call it a specification' or 'the skilled person must be enabled to perform the invention without prolonged research, enquiry and experiment' give a flavour of the problem they do not really help (see Mentor v Hollister  RPC 7 at 10-14).
 In the Mentor case, the Court of Appeal was attracted by the word 'routine', used by Aldous J at first instance. This word has the advantage that it enables a comparatively straightforward test along the lines of 'does this specification require the addressee of the specification to carry out tests, or developments, that go beyond the routine?' As Lloyd LJ said in that case, a phrase like 'routine trials' introduces a positive concept, easily understood and applied. Aldous J put it like this ( FSR 557 at 561):
'The subsection is concerned with the disclosure of the invention in the specification. Thus it is necessary to read the specification through the eyes of the skilled addressee to ascertain what is the invention that is disclosed. Even where patents relate to articles, the inventions disclosed in different specifications can be different in kind. For example, the invention disclosed may relate to an article which will perform a particular function or an article which is cheaper to make than similar articles. In the latter case, it is the very essence of the invention disclosed in the specification that the article can be made more cheaply and therefore to perform the invention the person skilled in the art must be able to make the article cheaply as described in the specification. In the former case, the person skilled in the art must be able to produce the article which will perform the function, as that is the invention disclosed.
The section requires the skilled man to be able to perform the invention, but does not lay down the limits as to the time and energy that the skilled man must spend seeking to perform the invention before it is insufficient. Clearly there must be a limit. The subsection, by using the words "clearly enough and completely enough," contemplates that patent specifications need not set out every detail necessary for performance, but can leave the skilled man to use his skill to perform the invention. In so doing he must seek success. He should not be required to carry out any prolonged research, enquiry or experiment. He may need to carry out the ordinary methods of trial and error, which involve no inventive step and generally are necessary in applying the particular discovery to produce a practical result. In each case, it is a question of fact, depending on the nature of the invention, whether the steps needed to perform the invention are ordinary steps of trial and error which a skilled man would realise would be necessary and normal to produce a practical result.
The section requires the skilled man to be able to perform the invention. Such a man is the ordinary addressee of the patent. He must be assumed to be possessed of the common general knowledge in the art and the necessary skill and expertise to apply that knowledge. He is the man of average skill and intelligence, but is not expected to be able to exercise any invention. In some arts he may have a degree, in others he will be a man with practical experience only. Further, in circumstances where the art encompasses more than one technology, the notional skilled person will be possessed of those technologies which may mean that he will have the knowledge of more than one person.'
 All the same, one must be on one's guard against formulations that gloss the statutory requirement as there is always a risk that they will end up being substituted for it. This is a particular risk where the subject of the specification is very complex and its development would anyway be expected to be accompanied by a great amount of work. What is 'prolonged' in this context? It is always necessary to keep a balance between the interests of the public and the interests of the patentee in the sense that it is necessary to guard against imposing too high a standard of disclosure merely because the subject matter is inherently complex. The general use of computers in modern technologies raises particular problems, because the writing of anything other than a trivial program requires a substantial amount of effort in writing and debugging (programming's version of trial and error), even though much programming requires no creative thought and a competent programmer will be equipped with substantial experience in his area of expertise. When such a programmer forms part of the team which is the notional addressee of a computer-based invention, it is essential to form a view of his capabilities."
"103. Whether the specification is sufficient or not is highly sensitive to the nature of the invention. The first step is to identify the invention and decide what it claims to enable the skilled man to do. Then one can ask whether the specification enables him to do it."
"When he has discovered that a difference is difference of degree, that distinguished extremes have between them a penumbra in which one gradually shades into the other, a tyro thinks to puzzle you by asking you where you are going to draw the line and an advocate of more experience will show the arbitrariness of the line proposed by putting cases very near it on one side or the other", Law and Science in Law Collected Legal Papers 1921, pp.232-233.
Standard for an appeal about insufficiency
"The need for appellate caution in reversing the judge's evaluation of the facts is based upon much more solid grounds than professional courtesy. It is because specific findings of fact, even by the most meticulous judge, are inherently an incomplete statement of the impression which was made upon him by the primary evidence. His expressed findings are always surrounded by a penumbra of imprecision as to emphasis, relative weight, minor qualification and nuance (as Renan said, la vérité est dans une nuance), of which time and language do not permit exact expression, but which may play an important part in the judge's overall evaluation. It would in my view be wrong to treat Benmax as authorising or requiring an appellate court to undertake a de novo evaluation of the facts in all cases in which no question of the credibility of witnesses is involved. Where the application of a legal standard such as negligence or obviousness involves no question of principle but is simply a matter of degree, an appellate court should be very cautious in differing from the judge's evaluation."
The same reasoning obviously also applies to a decision about insufficiency and the House of Lords so held in SmithKline Beecham's Patent  RPC 323 at  in the speech of Lord Hoffmann with which the other members of the House all agreed on this point.
The patent in suit
" A bit in use carries a very substantial weight, called the weight on bit, or WOB. This weight is made up of the drill collar and the rest of the drill string and is controlled by a tackle at the top of the string, which is supported by the derrick. Generally speaking there is a very easy introduction to the topic in the first chapter of the book called Rabia ('Oilwell Drilling Engineering: Principles and Practice' by Hussain Rabia), which is an undergraduate textbook located by Professor Cooper that is relied on as exemplifying the common general knowledge.
 The manner in which the bit penetrates rock depends generally upon the geometry of the cones in the bit and the shape of the teeth. Rounded carbide inserts are used in hard rock: they break the rock by crushing it as the tooth rolls into contact with the formation. The forces employed are substantial: the weight on bit may be as high as 60 tonnes and the rate of rotation 60 rpm. Softer formations require (in different degrees, depending upon the other drilling variables) a combination of both a crushing and a scraping action, for which the inserts or milled teeth will be more chisel-shaped. To ensure a degree of scrape, the cones are positioned so that their axes of rotation are not radial of the longitudinal axis of the hole, but are slightly offset so as either to lead or to lag a purely rolling motion, like this:
 The diagram shows a linear offset from the centre axis: obviously this can also be viewed as an angular offset from the radius of the bit. Whatever the precise orientation of the cones, the bit must be designed so that the rows of teeth each do their share of the work. It is helpful to think of the bit rotating and penetrating the formation: if a row of teeth follows the same path as another both will be doing less work. The following example is given by Professor Cooper, in which Ring A is cut by the heel or gage row of all three cones, ring B by cone 1, rings C and E by cone 2 and ring D by cone 3:
 This diagram shows that the cones in a given bit are always different from each other. Each will be subjected to different dynamic conditions at the bottom of the hole, and there is no a priori reason to suppose that they will tend to wear evenly. The movement of the teeth is composed of a rolling about the cone axis and a translational component resulting in gouging and scraping, and is not easy to visualize. The force on the teeth in contact with the formation is itself the force which rotates the cones as the drill rotates.
 The economics of drilling require that the bit be withdrawn from the hole as infrequently as reasonably possible. The rate of penetration needs to be as high as possible consistent with not causing premature wear of the bit, which obviously can destroy the advantage of a high rate of penetration if time is lost in early bit replacement. The process of 'tripping', which means the raising of the bit, is not trivial and is expensive—there may be thousands of feet of pipe to raise and uncouple. This means that durability of the drill is important and, with rate of penetration, is a primary concern of the user.
 Both before and after the priority date, the task of the manufacturer of drill bits has been to achieve durability with a good rate of penetration. It is impossible to monitor conditions at the bottom of a hole and very difficult to emulate them at the surface and so a designer's job depended (and for those who do not use a simulation program, still depends) upon his ability to examine 'dull' (worn) bits and change the design in response to the pattern of wear he saw. Uneven patterns of wear in the teeth and in the cone bearings will indicate the unsuitability of a particular design for a particular formation, and it is important to appreciate that a bit that is wholly inappropriate for one combination of formation, WOB and RPM may be entirely suitable to different combination of conditions. Mr Hall had wide experience of bit design and he provided this description of dull bit analysis:
'61. Analyzing the performance of previous bit designs and examination of these dull bits was the primary method of determining changes for a new bit design. Various conditions observed on dull bits would indicate improvements that could be made on a new design. …
62. For example, if a significant amount of breakage or chipping was consistently found in certain locations of the cutting structure of these dull bits, consideration would-be given to changing the number, shape or material used for the teeth in these locations. Adding rows of teeth to distribute the drilling forces may be considered. If this type of chipping or breakage was only found occasionally, the bit records for those bit runs. would be analyzed to determine if excessive WOB, excessive rotary speed or some other condition could have been the cause for the breakage. Consideration would also be given to the effects that changes to the tooth shape or quantity could have on the penetration rate of the bit. The experience and judgement of the bit designer would eventually be used to make changes to the design.
63. Another example would be if excessive wear was consistently noted in certain areas of the cutting structure, changes in the profile of the cone might be considered to decrease the amount of gouging and slicing that those teeth would experience. Again the effects that these changes would have on bit performance would be considered before changes would be made.
64. Unusual wear patterns observed on the bit would be considered in an attempt to determine possible causes for these conditions. Sharpening wear of the teeth on a bit can result from a condition known as "tracking". This condition is where as the cones rotate, one tooth falls into a crater on the bottom of the hole that has been caused by a previous tooth hitting at the same location. This condition causes a loss of penetration rate and results in wear to the cone shell as well as the teeth of the bit. Concentric rings worn into the cone shell can indicate that the bit is "running off-center" and is therefore not covering the bottom of the hole with cutting teeth in the desired locations as intended. This condition also results in decreased penetration rates and decreased bit life. Changes that would be considered to correct these conditions could include adding or removing. rows of teeth, changing the pitch scheme of teeth in the rows of teeth, changing the shape and length of teeth or other changes that a designers experience would indicate.'
 The manner in which the wear on a dull bit is reported is systematized. Both Professor Cooper and Mr Hall produced versions of a grading system proposed by the International Association of Drilling Contractors and are agreed that this system would be known to the skilled bit designer. Professor Cooper produced a 'Bit Record' which shows the history of a number of bits in a particular well, with the 'Dull Cond[ition]' specified for each.
 Accordingly, at the priority date drill bit design was in large part a matter for the skill, experience and intuition of the designer. Nobody has pointed to a comprehensive manual for drill bit designers, and I am sure that if one existed it would have been produced."
" Both patents are addressed to persons wishing both to design and use simulation systems for drill bit design. Although the claims are directed to methods of design, and are hence the concern of a designer, the underlying equipment, if I can put it that way, is a simulation system that the patents say is new. The Force Balancing patent uses a 'Rock Bit computer model' for the purpose of working out the dynamics of a rotating bit and describes the design of a bit in terms of a 'general nonlinear optimisation problem with bounds and nonlinear constraints' applied to design variables, objectives expressed in terms of the design variables and the bounds on the design variables and the constraints on the system. [He then summarised the other patent]. Plainly, therefore, the specifications are addressed to (1) engineers who understand drilling and drill bits (2) engineers who understand simulations and their graphical display and (3) if not included among the others, engineers who can understand the mathematics of the interaction of a drill tooth and rock and design the software necessary to model the dynamics and kinematics of the bit. I return to this subject in more detail below."
 There are seven parts of the background section of the Force Balancing specification, concerned with rotary drilling generally (paragraphs -), drill string oscillation (paragraphs  and ), optimal drilling with various formation types (paragraphs -), roller cone bit design (paragraphs -), tooth design (- and bottom hole analysis (paragraphs -).
We interpolate, that each of these seven parts are specifically given headings as set out by the Judge but each heading follows the word "Background", e.g. "Background: Rotary Drilling." Turning back to the Judge:
 The patent begins with a summary of the invention in paragraph :
' The present invention relates to down-hole drilling and especially to the optimisation of drill bit parameters. In particular it relates to a roller cone drill bit, a method of designing the same, and a rotary drilling system.'
 Paragraphs - set out very general background material, all of which I have covered in my discussion of the background above. The section on drill string oscillation is common general knowledge. Reduction of such oscillations is claimed as an advantage of drill bits designed according to the invention (paragraph ), but it is not otherwise referred to in the specification.
 The section concerned with Optimal Drilling with Various Formation Types (paragraphs -) is … all common general knowledge. Set out in summary form are the factors affecting how a formation is drilled and the types of bit suitable for soft formation (long teeth, high gouge), hard formation (short rounded teeth, no gouge) and medium formation (between the two).
 The next background section, 'Roller Cone Bit Design' …. was accepted by Mr Hall to be common general knowledge at the priority date. … I should refer to paragraphs  and . Paragraph  is concerned with the shape of the cones. It is pointed out that they need not be perfectly conical or frustoconical but may have what is called a 'swollen', that is bulging, axial profile. Apart from the shape of the cone itself, it is pointed out that both the angle between the axis of the cone and the radius of the bit (the offset angle) and the angle between the axis of the cone and the plane of the bottom of the hole (the journal angle, plainly related to the angle of the cone) are design parameters and affect the rolling of the cone, which, because it cannot necessarily roll true, causes gouging and scraping which, as is pointed out, is complex in nature.
 Paragraph  outlines the interrelationship of these design parameters and the effect of varying them. Two examples are given: cone angle and offset, which it is pointed out can be modified so as to increase or decrease the amount of bottom hole scraping. The other example is tooth length:
'Many other design parameters are limited in that an increase in one parameter may necessarily result in a decrease of another. For example, increases in tooth length may cause interference with the adjacent cones.'
 Paragraphs  to  are concerned with tooth design. Although the other paragraphs just set out a summary of the common general knowledge in respect of the range of shapes of teeth and their relationship to the formation intended to be drilled, I should just refer briefly to paragraph  because the shape of the tooth and its interaction with the formation is important.
'Chisel shaped inserts have opposing flats and a broad elongated crest resembling the teeth of a steel tooth bit. Chisel shaped inserts are used for drilling soft to medium formations. The elongated crest of the chisel insert is normally oriented in alignment with the axis of cone rotation. Thus, unlike spherical and conical inserts the chisel insert may be directionally oriented about its center axis. (This is true of any tooth which is not axially symmetric.) The axial angle of orientation is measured from the plane intersecting the center of the cone and the center of the tooth.'
 There is no doubt that oriented teeth were part of the common general knowledge of the designer. The angle of orientation affects the interaction of tooth and formation, and hence the relative movement (both rotational and translational) of the cone as the bit rotates. The gouging motion represents a translational movement between the tooth and the hole bottom. The movement of the tooth in the formation between the moment the tooth enters the formation and the moment it leaves takes a time and covers a distance determined by the rotation of the cone as it skids round the bottom of the hole. In the absence of a gouging motion, it should be remembered that the tooth movement can be visualised as a rolling movement about the point of the tooth, a movement whose translational element is small. The movement of the tooth in the coordinates of the hole bottom is shown by Professor Newland in Figure 7 in his principal report, explained further at transcript 1047 line 22.
 The final section on background, "Bottom Hole Analysis', sets the scene for the description of the invention. Paragraph  does not call for much comment: it trivially points out that bit design affects rate of penetration, and that rate of penetration plays a 'significant role' in the economics of drilling a well.
 Paragraph  begins to approach the heart of the invention:
' It has long been desirable to predict the development of bottom hole patterns on the basis of the controllable geometric parameters used in drill bit design, and complex mathematical models can simulate bottom hole patterns to a limited extent. To accomplish this it is necessary to understand first, the relationship between the tooth and the rock, and second, the relationship between the design of the drill bit and the movement of the tooth in relation to the rock. It is also known that these mechanisms are interdependent.'
This passage acknowledges the existence of 'complex mathematical models' that simulate bottom hole patterns. The bottom hole pattern is the cutting pattern left by the teeth in the formation at the bottom of the hole as the bit, subject to the WOB, rotates. The passage points out that in order to simulate the bottom hole pattern two things must be known: the way in which the tooth interacts with the formation and second 'the relationship between the design of the drill bit and the movement of the tooth in relation to the rock'. The specification acknowledges that it is known that these mechanisms are interdependent, and it could not be otherwise, because the forces acting on a cone are made up of the forces transmitted by the leg of the bit and the drag caused by the passage of the teeth through the rock along a path constrained by the geometry of the bit as it rotates in the hole.
 In paragraph  the specification continues with a description of the work done on these two problems, that is, the way in which the tooth interacts with the formation and the relationship between bit design and the movement of the tooth in relation to the rock:
' To better understand these relationships. much work has been done to determine the amount of rock removed by a single tooth of a drill bit. As can be seen by the forgoing discussion, this is a complex problem. For many years it has been known that rock failure is complex, and results from the many stresses arising from the combined movements and actions of the tooth of a rock bit. (Sikarskie, et al, PENETRATION PROBLEMS IN ROCK MECHANICS, ASME Rock Mechanics Symposium. 1973). Subsequently, work was been done to develop quantitative relationships between bit design and tooth-formation interaction. This has been accomplished by calculating the vertical, radial and tangential movement of the teeth relative to the hole bottom to accurately represent the gouging and scraping action of the teeth on roller cone bits (Ma, A NEW WAY TO CHARACTERIZE THE GOUGING SCRAPING ACTION OF ROLLER CONE BITS Society of Petroleum Engineers No 19448, 1989). More recently computer programs have been developed which predict and simulate the bottom hole patterns developed by roller cone bits by combining the complex movement of the teeth with a model of formation failure (Ma THE COMPUTER SIMULATION OF THE INTERACTION BETWEEN THE ROLLER BIT AND ROCK Society of Petroleum Engineers No 29922, 1995). Such formation failure models include a ductile model for removing the formation occupied by the tooth during its movement across the bottom of the hole and a fragile breakage model to represent the surrounding breakage.
 Currently roller cone bit designs remain the result of generations of modifications made to original designs. The modifications are based on years of experience in evaluating bit run records and dull bit conditions. Since drill bits are run under harsh conditions, far from view, and to destruction it is often very difficult to determine the cause of the failure of a bit. Roller cone bits are often disassembled in manufacturers' laboratories, but most often this process is in response to a customer's complaint regarding the product, when a verification of the materials is required. Engineers will visit the lab and attempt to perform a forensic analysis of the remains of a rock bit but with few exceptions there is generally little evidence to support their conclusions as to which component failed first and why. Since rock bits are run on different drilling rigs in different formations under different operating conditions it is extremely difficult [to] draw conclusion[s] from the dull conditions of the bits. As a result, evaluating dull bit conditions, their cause and determining design solutions is a very subjective process. What is known is that when the cutting structure or bearing system of a drill bit fails prematurely it can have a serious detrimental effect of the economics of drilling.'
 The two paragraphs appear to recognise both that numerical techniques exist to permit the prediction and simulation of bit action on formation by combining the movement of the teeth with a model of how the formation fails under the action of the teeth, and that these techniques have been incorporated in the computer program referred to in the Ma Paper. It is suggested that what is lacking is a way of using these techniques to replace the methods of design from bit analysis described in paragraph  and that this is described in paragraph :
' Though numerical methods are now available to model the bottom hole pattern produced by a roller cone bit there is no suggestion as to how this should be used to improve the design of the bits other than to predict the presence of obvious problems such as tracking. For example the best solution available for dealing with the problems of lateral vibration is a recommendation that roller cone bits should be run at low to moderate rotary speeds when drilling medium to hard formations to control bit vibrations and prolong life, and to use downhole vibration sensors. (Dykstra, et al; EXPERIMENTAL EVALUATIONS OF DRILL STRING DYNAMICS Amoco report Number F94-P-80 1994).'"
"3. A method of designing a roller cone drill bit comprising a plurality of arms, rotatable cutting structures mounted on respective ones of said arms and a plurality of teeth on each of said cutting structures, the method comprising the steps of:
(a) calculating the axial force acting on each tooth (18) on each cutting structure (16) of the roller cone drill bit (10);
(b) calculating the axial force acting on each cutting structure per revolution of the drill bit;
(c) comparing the axial force acting on each of said cutting structures with the axial force on the other ones of said cutting structures of the bit;
(d) adjusting at least one geometric parameter on the design of at least one of said cutting structures; and
(e) repeating steps (a) through (d) until substantially the same axial force will act on each cutting structure when the drill bit (10) is drilling into a formation.
6. A roller cone drill bit comprising:
- three arms;
- one rotatable cutting structure (16) mounted on each one of said arms; and
- a plurality of teeth (18) on each of said cutting structures;
wherein the number and locations of said teeth (18) are not identical between ones of said rotatable cutting structures (16);
characterised in that the axial force on each of said cutting structure is between thirty-one percent and thirty-five percent of the total of the axial force on the bit when the drill bit is drilling into a formation."
" At paragraph  the patent introduces the embodiments to be described with a statement that in those embodiments
'the roller cone bit designs should have substantially equal mechanical downforce on each of the cones. This is not trivial: without special design consideration, the weight on bit will NOT automatically be equalised among the cones.'
 Three causes of lack of balance are identified in paragraphs -. These are respectively (a) asymmetric cutting structures (cones) (b) offset effects and (c) tracking effects. The cones are asymmetric because the teeth (apart from the gage row) are in different places on each cone and are different in number. The gouging and scraping effect of the cone offset (paragraph 10 above) is different from row to row between the cones. Finally, a cone that tracks one of the others will have the effect that at least one cone will be cutting more formation than the other two and the bit is out of balance.
 Paragraph  suggests that substantially equalising the downforce per cone is very important and that this has been discovered by the patentee. Curiously, the words 'and greatly underestimated' are added to this assertion of importance, words that in a well-drafted document would tend to suggest that the patentee was here acknowledging that equal downforce on the cones had been recognised as at least one criterion even though its full importance had not been recognised. But this document is so poorly expressed that I am not willing to regard this phrase even as a straw in the wind. The paragraph promises that the application describes bit design procedures that provide optimization of downforce balancing 'as well as other parameters'.
 The principal advantage of equalising the downforce on the cones is said to lie in the reduction of vibration. Out-of-balance forces parallel to the axis of the hole will create a bending moment rotating about an axis perpendicular to the axis of the hole. This moment may be capable of coupling to the various oscillations of the drill string (paragraph ), so contributing to instability and to uneven wear. The reduction in vibration lies at the root of the improvements in wear performance set out in paragraph . The improvements for the designer follow from the criterion adopted (equal axial force or equal swept volume) and the use of a simulation system."
 The present invention uses a single element force-cutting relationship in order to develop the total force-cutting relationship of a cone and of an entire roller cone bit. Looking at Figure 1, each tooth, shown on the right side, can be thought of as composed of a collection of elements, such as are shown on the left side. Each element used has a square cross section with area Sc (its cross-section on the x-y plane) and length Le (along the z axis). The force-cutting relationship for this single element may be described by:
where Fze is the normal force and Fxe, Fye are side forces, respectively, is the compressive strength, Se the cutting depth and are coefficient associated with formation properties. These coefficients may be determined by lab test. A tooth or an insert can always be divided into several elements. Therefore, the total force on a tooth can be obtained by integrating equation (1) to (3). The single element force model used in the invention has significant advantage over the single tooth or single insert model used in most of the publications. The only way to obtain a force model is by lab test. There are many types of inserts used today for roller cone bit depending on the rock type drilled. If the single insert force model is used, a lot of tests have to be done and this is very difficult if not impossible. By using the element force model, only a few tests may be enough because any kind of insert or tooth can be always divided into elements. In other words, one element model may be applied to all kinds of inserts or teeth.
 After having the single element force model, the next step is to determine the interaction between inserts and the formation drilled. This step involves the determination of the tooth kinematics (local) from the bit and cone kinematics (global) as described bellow [sic].
(1) The bit kinematics is described by bit rotation speed, =RPM (revolutions per minute), and the rate of penetration, ROP. Both RPM and ROP may be considered as constant or as function with time.
(2) The cone kinematics is described by cone rotational speed. Each cone may have its own speed. The initial value is calculated from the bit geometric parameters or just estimated from experiment. In the calculation the cone speed may be changed based on the torque acting on the cone.
(3) At the initial time, t0, the hole bottom is considered as a plane and is meshed into small grids. The tooth is also meshed into grids (single elements). At any time t, the position of a tooth in space is fully determined. If the tooth is in interaction with the hole bottom, the hole bottom is updated and the cutting depth for each cutting element is calculated and the forces acting on the elements are obtained.
(4) The element forces are integrated into tooth forces, the tooth forces are integrated into cone forces, the cone forces are transferred into bearing forces and the bearing forces are integrated into bit forces.
(5) After the bit is fully drilled into the rock, these forces are recorded at each time step. A period time usually at least 10 seconds is simulated. The average forces may be considered as static forces and are used for evaluation of the balance condition of the cutting structure."
The alleged insufficiencies
 The insufficiency case as advanced has four aspects, and goes to the heart of the disclosure, since Smith say that the claims in effect require the development of a computer model to carry out the claimed method, and the amount of effort required to develop such a model is clearly undue. The four main heads, and the detailed matters on which Smith rely, are these:
(a) The skilled reader would be unable to set up the geometrical model of the bit, and in particular the transformations required for the kinematic calculations are inadequately disclosed, the volume matrix V3d0 being difficult to work out and not described;
(b) The skilled reader would be unable to calculate the forces acting on the teeth, and in particular paragraph  of the specification is misleading and wrong in assuming that force and volume may be equated (equations (1) to (3)) and no method of calculating forces for the purpose of paragraph  is described. The experiments, equipment and data required are not described.
(c) The skilled reader would be unable to calculate the cone-bit speed ratio, and in particular paragraph  (2) is obscure and may require a calculation nowhere described which is both complex and difficult; and
(d) The section of the specification entitled 'Design of a Force Balanced Roller Cone Bit' contains such inaccuracies and omissions as would prevent the skilled reader from designing a bit by following the instructions provided.
Outline of Halliburton's case
i) The motion of the cones and teeth can and should be modelled mathematically.
ii) The forces acting on the bit and its components, and the trajectories of the teeth through the rock, should also be modelled.
iii) The downwards forces on each cone should be balanced as between the cones.
iv) This should be done by calculating the forces on each tooth and thus on each cone, and adjusting the design and recalculating those forces until such balance is achieved.
The sufficiency of the specific description
(a) A kinematic model?
" Mr Hall accepted that this was 'a lot of work'. Even if it were legitimate to look at the Ma book, which is not shown to be common general knowledge, this evidence would support a suggestion of insufficiency. Without the Ma book not enough is disclosed, and it was not suggested that the Ma paper helped in this respect. As I have indicated, I feel uneasy with the allegation of insufficiency based on geometric and kinematic considerations alone, but in the end I think that the balance of the evidence tips in favour of a conclusion of insufficiency."
"The problem is what this [i.e. ordinary CAD] software cannot do is simulate the motion of the cones and the drill bit simultaneously in such a way that the trajectory of the teeth can be followed without having the appropriate sub-program which would enable equations like the equations in chapter 2 of Ma." (Transcript p.850)
And, when pressed:
"What I am saying is that these are equations which are difficult to derive, and they are complicated, and they include a lot of variables and angles and you have to go through that agony in order to be able to say where the teeth are and reference to the formation. Whatever method of calculation you use, in effect, you come down to those equations." (p.851-2).
"Ma is using these equations [i.e. those in the book] which he had published some 10 years earlier in a paper to the American Society of Mechanical Engineers with his Professor J.J. Azar when he worked as a research fellow in the United States at the University of Tulsa. That was a refereed paper -- you can see that from the credentials of the paper and the dates of receipt and publication -- of the ASME and that was regarded at the time as a major step forward in understanding the dynamics of these drill bits. If it had not been, it would not have been published and nor would Azar have been associated with it. That is what Ma is quoting here. All I am saying is that is a difficult and big calculation. It merited a scientific paper when it was done and it remains a significant feat of 3-D geometry for an engineer." (p.853).
"Even if I took the equations straight out of Ma's book, it would still be a significant project because you have got to understand all the aspects of them and get the correct numbers into them and model this. Following all those points on every tooth, into contact with the ground and out of contact with the ground, is just a huge task." (Professor Newland at transcript p.864)
(b) bit/cone speed ratio?
"Each cone may have its own speed. The initial value is calculated from the bit geometric parameters or just estimated from experiment. In the calculation the cone speed may be changed based on the torque acting on the cone."
(c) A force model?
"According to equation (1) the force acting on an element is proportional to the rock volume removed by that element".
Actually equation (1) does not mention rock volume. But since rock volume removed will also be linearly proportional to depth, Sc, one can see that this sentence confirms that an assumption of linearity has been made.
"Equation (1) is just wrong. It was not established that the skilled man would appreciate that this error existed, let alone that it was obvious." 
"If, as I consider a fair reading of the specification indicates, these equations are intended to provide a guide for the construction of the model, the model is wrong and cannot give useful results." 
A cross-reference to the Ma Paper for Sufficiency?
" This passage seems to me to carry on the discussion in paragraph  of the Ma paper, which is concerned with the modelling of the bottom hole pattern, and it is dismissive in tone, suggesting that Ma's program can be used only to predict the presence of obvious problems such as tracking. Halliburton contend that the disclosure of the Ma paper, which is rather more comprehensive than paragraphs  and  suggest, is incorporated by reference. The words used are not, in my judgment, capable of incorporating this disclosure into the disclosure of the patent. Patent specifications should be complete in themselves and while they must be read like any other document these words do no more than dismiss the Ma paper (and the other citations) as ineffective components of the state of the art."
" The reference to the Ma paper is summarised in paragraph 29 above. As a matter of construction, this is the thinnest possible basis for a suggestion that the disclosure of the paper is to be incorporated in the patent. It seems to me that the specification does not point the addressee in the direction of the Ma paper for the purpose of supplementing its disclosure for any purpose. It is a description of the background prior art. I think that the Ma paper is really disclosed as a record of the existence of a computer program which does not do what the claim requires, in other words a failed proposal. If the patentee had wished to use the disclosure of Ma, the cross-reference should have been express.
 In general, cross-referencing for the purpose of supplementing the disclosure is highly undesirable, and is not permitted by the EPO, which deals with the matter as follows in its Guidelines for examination Chapter C-II:
'4.18 Reference documents
References in European patent applications to other documents may relate either to the background art or to part of the disclosure of the invention.
Where the reference document relates to the background art, it may be in the application as originally filed or introduced at a later date (see II, 4.3 and 4.4).
Where the reference document relates directly to the disclosure of the invention (e.g. details of one of the components of a claimed apparatus), then the examiner should first consider whether knowing what is in the reference document is in fact essential for carrying out the invention as meant by Art. 83:
If not essential, the usual expression "which is hereby incorporated by reference", or any expression of the same kind, should be deleted from the description.
If matter in the document referred to is essential to satisfy the requirements of Art. 83, the examiner should require the deletion of the above-mentioned expression and that, instead, the matter is expressly incorporated into the description, because the patent specification should, regarding the essential features of the invention, be self-contained, i.e. capable of being understood without reference to any other document. One should also bear in mind that reference documents are not part of the text to be translated pursuant to Art. 65.'
 I am not concerned with how an application is to be examined, but this principle is a sound one. If the disclosure is essential to the patent that fact should be made abundantly clear. As a matter of the ordinary principles of document construction it is not permissible to exclude the possibility of a cross-reference for essential material: but the court must, I think, be on its guard to ensure that the cross-reference is a proper one. This is not such a cross-reference.
a) First and most obviously it simply does not say that.
b) The patent puts forward its element method as superior to "single tooth or single insert models used in most of the publications." Faced with abject failure by reason of impossibility on the patentee's specific proposal, why should the skilled addressee expect, buried in the acknowledgement of the prior art, anything useful for implementation of the invention? Indeed if he did go to Ma he would find it to be a single tooth model, said by the patentee to be inferior.
c) The actual reference comes under the heading: "Background: Bottom Hole Analysis" which is not an indication that Ma is relevant to bit design.
d) There is no suggestion in the passage that the Ma paper contains a force model. So why would the skilled addressee expect to find one there at all, still less one that might be adapted for force balancing?
e) The very presentation of the invention is not consistent with the notion that you can use existing methods of calculation but with the difference that you aim to force balance – just add the "big idea" to known techniques. The whole method is presented as new in itself, as for instance in  where the steps of claim 3 are set out as a completely new calculation.
f) The patent actually goes out of its way, in  to identify three publications of which it says "all of which are hereby incorporated by reference". The Ma paper is not one of them. If the author wanted the reader to understand that Ma was also incorporated by reference, this was surely a place to do it.
a) In the key areas to which we have referred above, the Professor's evidence (as an engineer and computer modeler) is the relevant evidence – that was not Mr Hall's expertise.
b) As regard the bit/cone speed ratio problem, the judge particularly relied on Mr Hall's evidence.
c) Mr Hall had given unsatisfactory evidence in a number of respects (for the details see the judgment at ,  and ).
d) The Judge was very alive to the point and weighed it carefully:
" The last objection that Halliburton make to this formidable case on insufficiency depends upon the contrast they draw between the wide experience of Mr Hall on the one hand and Professor Newland's lack of specific experience in the industry on the other. It was submitted that Professor Newland's lack of experience deprives his evidence of much weight when it is set against that of Mr Hall. I reject this submission. I have already indicated that in a number of respects Mr Hall's evidence was not consistent. No aspect of the insufficiencies that I find established depends upon a close knowledge of the drilling industry or of the manufacture of drills. They are, on the contrary, really objections based upon the difficulty of constructing a model given the data and other information made available by the specification. The objections of insufficiency that I have set out in paragraph 136 above are all established."