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5.6.7.2 Clear enough and complete enough disclosure s40(2)(a)

Date Published

Key Legislation:

Patents Act:

  • s40(2) Disclose the invention in a manner which is clear enough and complete enough
  • s40(3) Claims must be clear and succinct and supported
  • s102 What amendments are not allowable?
  • s223 Extensions of time  

Other referenced materials:

PCT Articles & Rules:

Overview

Subsection 40(2)(a) states that a complete specification (description, claims, and drawings) must ‘disclose the invention in a manner which is clear enough and complete enough for the invention to be performed by a person skilled in the relevant art’.

This provision reflects a fundamental principle of international patent law; in exchange for the exclusive rights given to the patentee, the patentee must share with the public the information necessary to make and use the invention.

The complete specification must provide sufficient information to enable the skilled person to perform the invention over the whole width of the claims, without undue burden or the need for further invention.

This is often referred to as sufficiency.

Sufficiency is most likely to relate to one of the two following circumstances:

  • ​​​​​​​Classical insufficiency where the teaching of the patent does not enable the skilled person to perform the invention without the need for further invention, or where “prolonged research, enquiry or experiment” is required in order to work the invention; or
  • Insufficiency by excessive claim breadth (sometimes referred to as Biogen insufficiency) where there may be an enabling disclosure for something falling within the scope of the claim, but not across the full breadth of the claim.

Relevant date

The specification must have the necessary information to satisfy the requirement of being clear enough and complete enough at the filing date of the complete specification. This is the practical effect of s102(1), which is that an insufficient disclosure cannot be rectified by adding new matter after the filing date of the application. 

Compliance with s40(2)(a) is determined taking into account the common general knowledge of the person skilled in the art at the filing date.

Where the invention involves biological material, the applicant may rely on a deposit made under the Budapest Treaty to meet the clear enough and complete enough disclosure requirement. A deposit under the Budapest Treaty must be made on or before the filing date of the complete application. However, to gain the earliest possible priority date, the deposit should be made on or before the filing date of the priority document.

​​​​​​​Late filing of a deposit under the Budapest Treaty cannot be rectified by an extension of time under s223 (as there is no relevant time period to be extended), nor overcome by filing a divisional application. (see 5.6.7.6 Complete Disclosure Micro-Organisms and Other Life Forms (Budapest Treaty))

Examination practice

Compliance with s40(2)(a) is a question of fact. Whether a specification discloses a method that will actually perform the invention is a matter which can best be determined by receiving evidence from the person skilled in the art (Universal Oil Products Co. v Monsanto (1972) 46 ALJR 658). If the specification, on its face, would appear to the person skilled in the art to lack a clear enough and complete enough disclosure, the onus of establishing that the invention is described in sufficient detail lies with the applicant. (Explanatory Memorandum).

While the sufficiency requirement must be satisfied at the filing date, post filing evidence may be used to establish the common general knowledge at the filing date and how the skilled person would understand the teaching of the specification as filed (BASF Corporation [2019] APO 34).

Arguments that a particular feature or step would be “obvious” based on common general knowledge are unlikely to overcome a sufficiency objection. Sufficiency is based on the disclosure given in the complete specification as filed. While the PSA would read this information with the common general knowledge in the art to help them understand the invention described, this does not go so far as to supplement, or add to, the disclosed features from the common general knowledge that have not been described.

Examiners should take the following approach, set out in CSR Building Products Limited v United States Gypsum Company (2015) APO 72 to assess compliance with s40(2)(a):

  • Construe the claims to determine the scope of invention as claimed;
  • Construe the description to determine what it discloses to the person skilled in the art; and
  • Decide whether the specification provides an enabling disclosure of all the things that fall within the scope of the claims.

This approach was further expanded in Evolva SA [2017] APO 57, where the third part was taken to comprise two enquiries:

  1. Is it plausible that the invention can be worked across the full scope of the claim; and
  2. Can the invention be performed across the full scope of the claim without undue burden?

​​​​​​​Further information on each aspect of this approach is provided below under each subheading.​​​​​​​​​​​​​​

Enabling disclosure

Both s40(2)(a) and s40(3) require the specification to provide an enabling disclosure of the claimed invention. Under s40(2)(a), the clear enough and complete enough (enabling) disclosure must be found in the complete specification. In contrast, for s.40(3), the enabling disclosure supporting the claims must be found in the body of the specification (the description and any drawings, graphics and photographs and sequence listing).

​​​​​​​The enabling disclosure for s40 is not the same as the enabling disclosure required in a novelty citation. For novelty purposes, the person skilled in the art has no knowledge of the claimed invention and consequently the enabling disclosure must provide ‘clear and unmistakable directions’ to do what is claimed. A s40 enabling disclosure is one that provides the person skilled in the art with sufficient information to achieve what is claimed without undue burden or the need for further invention.

Underpinning the s40(2)(a) consideration (sufficiency consideration) is the premise that the person skilled in the art who has read the specification knows what is claimed, what is to be achieved, and is approaching the task with the aim of making the invention work. The requirement under subsection 40(2)(a) is not absolute. The specification need only be clear enough and complete enough for the skilled person to work the invention, and a reasonable degree of trial and error is permissible. If the skilled person is faced with alternatives, it is generally assumed that they would choose one that will work.

Choice of components and starting materials

Where a specific component from a broad class or group is necessary to perform the invention as claimed, the specification must identify that specific component. If the specification merely refers to the broad class or group, the disclosure is not enabling.

Unless the starting materials in a process, or the ingredients in a composition, are part of the common general knowledge, the specification must disclose a method of preparing those starting materials or ingredients from known materials.

A statement in the specification that the starting material/ingredient is obtainable, or otherwise known, should generally be accepted. Reference to a material/ingredient by a trade name or another commercial identification may be considered on its face an indication that the material/ingredient is known (see also 5.6.7.2 Clear enough and complete enough disclosure (Trade marks in specifications)).

Repeatability

If the successful performance of an invention is purely dependent on chance or is unrepeatable, there is a fundamental insufficiency in the description of the invention and it cannot be considered enabled.

A different scenario is where repeated success of an invention is assured but this is accompanied by a proportion of failures. For example, this can happen in the manufacture of small magnetic cores or electronic components. Provided the successes can be readily separated from the failures by a non-destructive testing procedure, the disclosure of the invention will be sufficiently enabling.

Principle of general application

A principle of general application relates to a claim, or an element of the claim, stated in general terms; the question is whether the specification enables the broader “principle” or whether there is only enablement of a narrower range of integers. In such cases the claim will be enabled if a skilled person can reasonably expect the invention to work with anything that falls within the general term (Kirin-Amgen Inc v Hoescht Marion Roussel Ltd (2005) RPC 9).

Although most sufficiency objections are likely to arise because of the breadth of a claim, and whether the claim (or an integer in a claim) can be considered a principle of general application, it is important to understand that claims are not objectionable merely because they are broad.

In a simple example, a reference in a claim to ‘connecting means’ will be enabled if the claimed invention can be reasonably expected to work with any means of connection; the applicant does not need to have experimented with all of them. Similarly, in the chemical arts the scope of the general terms ‘leaving group’ or ‘protecting group’ is well understood and an example of one member of the group would normally provide an enabling disclosure for a claim referring to all members.

Where the claims are more broadly drafted, they may be considered enabled if, prima facie:

  • the disclosure teaches a principle that the person skilled in the art would need to follow to achieve each embodiment falling within a claim; and
  • the specification discloses at least one application of the principle and provides sufficient information for the person skilled in the art to perform alternative applications of the principle in a way that, while not explicitly disclosed, would nevertheless be obvious to the person skilled in the art (T 484​​​​​​​/92).​​​​​​​

Plausibility

When considering whether it is plausible that the invention can be worked across the full scope of the claim, the examiner considers whether there is a technically sound or credible basis for the principle of general application. An examiner will generally base an objection, and any corresponding rebuttal, on substantiated technical reasoning or on prior art.

​​​​​​​If it is not plausible that the invention can be worked over the full scope of the claim, the disclosure is not sufficient. If lack of plausibility has been established, putting the invention into practice would inevitably require an undue burden. It is not necessary to make a strong case regarding undue burden if an invention is considered implausible.

If the claimed feature is considered plausible, the question of undue burden must still be addressed.

​​​​​​​Failure to meet either or both enquiries, that is the question of plausibility or the question of undue burden, will mean there is a lack of sufficiency.

Undue burden

If the person skilled in the art cannot perform the disclosed invention without prolonged research or tests that go beyond routine trial and error, it would be an ‘undue burden’. In deciding whether this is the case, examiners should consider the nature of the invention and the abilities of the skilled person, including the degree to which they may normally carry out routine trials and experimentation. Experimentation which requires inventiveness or discovery of something new to work the invention would likely indicate that the specification lacks sufficiency.​​​​​​​

Nature of the invention

Examiners should take care with particularly complex fields of invention. Examiners need to avoid imposing too high a standard of disclosure just because the subject matter is inherently complex. Where the specification is particularly complex, performing the invention would be expected to be accompanied by a great amount of work.

​​​​​​​For example, the development time for a new pencil sharpener is likely to be much shorter than the development time for a nuclear fusion reactor.

Where the invention involves a new principle of general application and the claimed technique has broad applicability, if the specification provides an enabling disclosure of one practical application of the principle, implementation of the principle for an alternative application may not involve an undue burden.  However, this will depend on the facts of the case and be influenced by the extent to which the information in the specification could be used to develop further embodiments without a major conceptual leap. (Kirin Amgen/Erythropoietin II T 636/97 at [4.5])

Abilities of the skilled person

The degree of skill or knowledge expected of the person skilled in the art will depend on the complexity of the relevant art. The skilled person is not a person of exceptional skill or knowledge. But they must have a reasonable degree of skill and common knowledge of the art and be able to use this in conducting trials and correcting obvious errors in the specification that can readily be corrected.

No objection would arise where there are errors or omissions in the specification, but the person skilled in the art would recognise that there was an error (or information missing) in the specification and could rectify this without making further invention. 

See also 5.5.2.2 The Addressee for additional guidance identifying the person of skill in the art.

See also 5.6.7.2 Legal principles on Undue Burden for additional background information.

Clarity of Disclosure

Similar to the approach in "5.6.7.1 Claims are clear and succinct", examiners are not expected to proof-read the specification to identify each and every clarity issue of the disclosure. Examiners should adopt a practical and common-sense approach, raising objections only on significant deficiencies they become aware of during the course of examination.

The disclosure of a complete specification will not be clear enough if it is so fundamentally deficient that a person skilled in the art, having read the specification, could not understand how to perform the claimed invention.  In these circumstances, it is also unlikely that a reasonable search could be conducted of the invention defined in the claims.

No objection should be taken under s40(2)(a) merely because it is possible to describe an invention more clearly.

A specification should not contain superfluous or irrelevant matter.  Complicated mathematical calculations and analyses are undesirable, unless they are necessary for a full understanding of the invention.  However, only in the most extreme cases should the applicant be requested to shorten an inordinately long specification.

The description should not contain passages which confuse the scope of the invention.  However, phrases such as “the invention should be taken to include any modifications, whether novel or not” do not provide a meaningful disclosure of any subject matter and should be construed as such.  

Where parts of the description or particular drawings, graphics or photographs do not exemplify the invention claimed, e.g. where they are included as explanation of the invention, as comparative examples, or where they relate to prior art, this should be clearly indicated.

Specific scenarios and claim types

Discrete methods or products must be individually enabled

Disclosing one method of making a product with only one embodiment provides an enabling disclosure to the product per se. An applicant is not required to enable the person skilled in the art to make the same product by all possible methods (Generics (UK) Limited and others v H Lundbeck A/S (2009) UKHL 12; (2009) RPC 13 at paragraph 80).  

Where the claims include a number of discrete processes or products, each must be sufficiently disclosed and enabled, (Chiron Corp and Ors v Murex Diagnostics Ltd and Ors (1996) RPC 535 at pages 612 and 613). The disclosure of a single embodiment will not always satisfy the requirement for an enabling disclosure (Biogen Inc v Medeva PLC (1997) RPC 1 at page 22).

Where the claims encompass a broad field (for example, a broad class of products), an enabling disclosure may involve several generic method(s) of production (each enabling different subgroups within the broad field), or several examples or alternative embodiments or variations, sufficient to enable the person skilled in the art to perform the invention over the whole scope of the claims, without an unreasonable amount of trial and error.

Claiming by result

The criteria for an enabling disclosure are the same regardless of the claim type and are not stricter where a claim is limited by the result to be achieved.

Where a claim defines the invention in terms of desirable results, the claim should be construed to determine its scope.  Properly construed, the claim may encompass, for example, a class of products having particular properties, a class of processes that achieve a particular result, or a combination of these in a product by process claim.

Where the claim encompasses a class of products or processes, the specification will need to provide enough instruction for the skilled person to make each product and/or work all the processes that are encompassed by the claim, without undue burden or the need for further invention (see 5.6.7.3 Support for the claims for additional information).

Individual features defined by function

Where a feature of a claim is defined in functional terms, the person skilled in the art must understand it and be able to implement it (T 568/97).

A claim may broadly define a feature in terms of its function, where only one example of the feature has been explicitly disclosed, provided the person skilled in the art would appreciate that other means could be used for the same function. Where a functional feature in a claim encompasses a vast range of possible alternatives, the claim will not be enabled unless the person skilled in the art would reasonably expect the claimed invention to work with anything that falls within the scope of the functional definition.

Where the claim defines a class of functionally-defined products and the specification teaches a process for making a vast number of products that may or may not have the function as claimed, the disclosure will not be enabling for the claimed invention unless it teaches the person skilled in the art how to ascertain which of the products actually has the required properties (American Home Products Corp v Novartis Pharmaceuticals UK Ltd (2001) RPC 8 at paragraphs 39 - 43). Where a screening method is provided, a further consideration is whether the time required to screen every product would impose an undue burden on the person skilled in the art.

Parametric claims

Where the claims define the invention in terms of parameters, the specification as filed must disclose a means to achieve and/or determine the parameter values, unless a person skilled in the art would know what method to use or all methods would yield the same result.

For example, where a claimed product comprises two components and each component is selected from separate vast lists, performing the invention requires the person skilled in the art to select a pair of components to achieve desirable characteristics in the final product. The specification would lack an enabling disclosure where:

  • the specification contains little or no guidance on how to select a pair of components which would achieve the desired characteristics in the resulting product; and/or
  • the specification provides no information on how the desirable characteristics could be measured or otherwise determined in a product containing any pair of components.

A consideration of whether performing the invention over the whole scope of the claims would impose an undue burden is also relevant (see also 5.5.4.6 Parametric Claims under Claim Construction).

Reach-through claims

‘Reach-through’ claims define compounds in terms of specific properties identified in a screening assay. This style of claim is more prevalent in the chemical and biochemical areas, and in many cases such claims will not be enabled.  

Where the specification provides a screening method, consider whether the time required to screen every product would impose an undue burden in requiring substantial experimentation by trial and error on the person skilled in the art.

See also 5.6.7.3 Support for the claims for additional information. 

Synergism

Where claims are to a composition comprising a ‘synergistic’ combination of 2 or more chemical compounds, the specification will need to contain guidance on how the synergistic result is achieved. For example, the concentrations or ratios of the compounds that will provide the synergistic result may need to be disclosed. Synergism between chemical compounds is generally unpredictable. Not all combinations of the specified compounds will necessarily exhibit the claimed property.

Without this guidance there may be undue burden on the skilled person to test all possible combinations to determine those that fall within the scope of the claims.

Reliance on cross-references

A specification should provide a clear enough and complete enough disclosure of the claimed invention without reference to other documents.

If the specification relies on a cross-reference to disclose details required to perform the invention, it is not sufficiently enabling. In this scenario an amendment to insert the cross-referenced material into the specification is required before the application can be accepted. Amendments which propose to insert the relevant cross-referenced material are generally allowable under s102(1), provided the material was verifiably present in the referenced document at the filing date of the application under examination (see also 5.3.2.4 Substitute documents and 5.7.4.2 Allowability under section 102(1)).

Cross-references to other documents merely to provide background information, prior art, or to illustrate subsidiary features, are not objectionable provided that:

  • the cross-referenced document(s) contained the information at the filing date of the specification; and
  • where the cross-referenced document is a patent document, it was filed on or before the filing date of the specification being examined; or
  • where the cross-referenced document is a non-patent document, it was publicly available on or before the filing date of the specification.

For example, a description that referred to feature X, noting that X could be in any form, but preferably in the form disclosed in a cross-reference, would not be objectionable if a claim merely referred to feature X.  However, if the claim specified the particular form disclosed in the reference, the absence of the relevant disclosure would be objectionable under s40(2)(a), and an amendment would be required to insert the relevant cross-referenced material before the application could be accepted.

The content of the cross-referenced patent or non-patent document at the filing date of the specification being examined will need to be verifiable.

Incorporation by reference of matter contained in non-patent documents may be problematic, as there may be doubt as to the content of the documents at the filing date of the application under examination.  

Where a cross-referenced document is not readily available to examiners, the applicant should be requested to provide a copy. The applicant should also be requested to provide a translation if the cross-referenced document is not in English. For translations filed on or before 25 September 2019, a certificate of verification for translation must also be provided.

Where a reference to an internet page is essential for sufficient disclosure of the claimed invention, a copy of a verifiably dated web page showing its contents at the filing date must be provided before an amendment can be allowed under s.102 to add such matter to the complete specification. ​​​​​​​

Note that where the content of a cross-referenced non-patent document is required in order to perform the claimed invention and there is doubt as to its disclosure at the filing date of an application, the application may lack a clear enough and complete enough disclosure and any proposed amendments may not be allowable. In these situations, where the issue has not been resolved despite adverse reports, examiners should consult Patent Oppositions.

Disclaimers

If the specification refers to another document for the purposes of a disclaimer or to exclude subject matter from a claim, the specification can be amended to include the cross-referenced material as long as the amendment does not result in the specification disclosing or claiming new matter (s102(1)). See also Cross-references and Disclaimers under '5.6.7.1 Claims are Clear and Succinct'.

Trade marks in specifications

A trade mark is used to identify the source or origin of a good, not its properties. Where a feature of a claimed invention is characterised by way of a trade mark and the characterisation introduces uncertainty in how the invention is performed, the examiner should object that the invention has not been disclosed in a clear enough and complete enough manner. (See also Trade marks in claims under Support).

Colour drawings, graphics, and photographs

It is rare that the use of colour drawings, graphics or photographs is required to satisfy a clear enough and complete enough disclosure of an invention. The use of colour drawings, graphics or photographs is permitted in certain circumstances (see Drawings, graphics, photographs and colour under Formal Requirements of the Specification). The acceptability of such pages is generally a formality issue handled by CEG, with there being an expectation that an applicant files black and white drawings, graphics or photographs where possible. Any queries regarding the acceptability (from a reproducability perspective) of colour drawings, graphics or photographs should be referred to CEG.

Where colour is important to an invention, use of a standard colour reference chart (such as the Royal Horticultural Society Colour Chart) may be an alternative to using colour drawings, graphics, or photographs.

Relative terms

A complete specification does not lack a clear enough and complete enough disclosure just because a relative term has been used to describe an invention and some experimentation of a routine nature is necessary to perform the invention. However, the person skilled in the art must be able to interpret the scope of the relative term and what is encompassed by the claims.

​​​​​​​A patent related to a diving suit with a "close fit", such that only a "minimum air layer" could form between the suit and the diver's body did not fail due to insufficiency, even though the specification made use of a relative term which did not describe how much room there should be between the diver and the suit (Poseidon Industri A.B. v Cerosa Limited (1982) FSR 209). In this case, "a little ordinary trial and error" would be sufficient to ascertain the satisfactory minimum layer of air.

See also Relative terms in 5.5.4 Claim construction.

Cyclic inventions

It is possible for ‘cyclic inventions’ to occur in concurrent cases. For example, one specification describes the preparation of B from A; another describes the preparation of A from B. Neither specification discloses any other means of preparation of either A or B. Both A and B are presumed to be new compounds or new classes of compounds, since otherwise one of the inventions may not be novel.

As a general rule, it is not permissible to use one specification to assist in the interpretation of the other, even if filed by the same applicant (Pfizer Inc v Commissioner of Patents (2005) FCA 137). The fact that one specification contradicts the other is not a basis for an objection, as each application stands on its own. Instead, examiners should raise an objection of lack of clear enough and complete enough disclosure on both applications and seek clarification of the matter.

Contravention of laws of nature 

If an invention contravenes the laws of nature or is absurd in view of current knowledge (for example, a perpetual motion machine), an objection may be raised due to lack of clear enough and complete enough disclosure. This is because having regard to the known laws of nature, the invention is not capable of performing in the manner described.

Other grounds of objection which examiners should consider are:

Claims as the basis of disclosure

Where the only disclosure of a relevant feature occurs in the claims, it is proper to have regard to the claims to determine whether the claimed invention complies with s40(2)(a).

However, the mention of a feature in a claim does not necessarily establish an enabling disclosure of the claimed invention for the purposes of s40(2)(a) – it is necessary to construe the complete specification as a whole to establish what the disclosure enables the person skilled in the art to do. For example, an application will not comply with s40(2)(a) where:

  • a feature referred to only in a claim is inconsistent with the disclosure as a whole; or
  • a feature referred to only in a claim does not provide sufficient information to enable the person skilled in the art to perform the invention over the whole width of the claim, without undue burden or the need for further invention (and the feature is not otherwise sufficiently enabled by the common general knowledge in the art).

See also related Support topic on Features disclosed only in the claims.

Objections under s40(2)(a)

Section 40 requires a “point-in-time” consideration. Compliance with s40 is determined based on the disclosure provided in the specification read in view of the common general knowledge in the art as of the filing date of the application. This means objections should not be taken based on speculation that an alternative embodiment falling within the scope of the claims may be developed later that could result in hypothetical “future infringement” of a claim.

Unless the examiner is reasonably satisfied, on the balance of probabilities, that the complete specification complies with s40(2)(a), they should raise an objection. 

The objection must include logical reasons why the complete specification does not disclose the claimed invention in a manner which is clear enough and complete enough for the person skilled in the art to perform the invention over the whole width of the claims. The reasoning may be based on, for example the examiner’s personal knowledge, statements made in the specification, the prior art, or other materials on file (for example, in third party re-examination requests or documents filed under s27).

If the claims contain ambiguity that causes doubt about the scope of the invention, the examiner may make an objection under s40(2)(a) that the invention has not been enabled over the whole width of the claims. However, in extreme cases where the scope of the claims cannot be determined, it may be preferable to object to a lack of clarity in the claims. Objections under s40(2)(a) and/or s40(3) can be raised, where relevant, after the clarity objection has been resolved.

Note: Although a deficiency may lie predominantly in the clarity or the completeness of the disclosure, objections under s40(2)(a) should use the phrase ‘clear enough and complete enough disclosure’.

Considering a response to an objection under s40(2)(a)

Where the applicant provides evidence or credible and plausible submissions that adequately address the examiner’s concerns by establishing that, on the balance of probabilities, the disclosure is clear enough and complete enough, the objection should be withdrawn. A mere assertion will not be enough to overcome a well-reasoned objection under s40(2)(a).

Objections under s40(2)(a) cannot be overcome by the addition of new matter extending beyond that disclosed by the specification as filed (together with other prescribed documents), since this is prohibited under s102(1). However, an objection to an excessive breadth of the claims may be remedied by restricting the scope of the claims. 

Where an issue is not resolved despite subsequent adverse reports, the supervising examiner should consult Patent Oppositions on the further progress of the case, including whether to set the matter for hearing with the intent to refuse the application.

Legal principles

Clear enough and complete enough

The test for a clear enough and complete enough disclosure was provided in Kirin-Amgen Inc v Hoechst Marion Roussel (2004) UKHL 46; (2005) RPC 9 at paragraph 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 person to do. Then one can ask whether the specification enables them to do it."

For the purposes of s.40(2)(a) ‘the invention’ is the claimed invention:

"In order to decide whether the specification is sufficient, it is … first necessary to decide what the invention is. That must be found by reading and construing the claims, in which the inventor identifies what he claims to be his invention." (Lord Hoffmann in H. Lundbeck A/S v Generics (UK) Ltd (2008) EWCA Civ 311; (2008) RPC 19 at paragraph 29).

Where a claim is to a product per se, the product is the invention. Where a claim is to a process, the invention is working the process (H. Lundbeck [2008] at paragraphs 27 and 30).

In general, for a ‘product by process’ claim where the product is known, the invention is the process by which the product is made or otherwise obtained (Kirin-Amgen [2005] at paragraph 109).

Enabling disclosure 

Biogen v Medeva (1997) RPC 1 at 48 explained the concept of an enabling disclosure:

"the specification must enable the invention to be performed to the full extent of the monopoly claimed. If the [specification] discloses a principle capable of general application, the claims may be in correspondingly general terms. The [applicant] need not show that he has proved its application in every individual instance. On the other hand, if the claims include a number of discrete methods or products, the [applicant] must enable the invention to be performed in respect of each of them."

Where there are different embodiments, each must be sufficiently disclosed and enabled (Chiron Corp and Ors v Murex Diagnostics Ltd and Ors (1996) RPC 535 at pages 612 and 613). In this situation, the disclosure of a single embodiment will not always satisfy the requirement for an enabling disclosure (Biogen Inc v Medeva PLC (1997) RPC 1 at page 22).

Where the claim defines a class of functionally defined products and the specification teaches a process for making a vast number of products that may or may not have the function as claimed, the disclosure will not be enabling for the claimed invention, unless it teaches the person skilled in the art how to ascertain which of the products actually has the required properties (American Home Products Corp v Novartis Pharmaceuticals UK Ltd (2001) RPC 8 at paragraphs 39 – 43).

If a feature in a claim has a limiting effect but the specification does not teach how the feature is to be achieved, or how the presence or absence of the feature can be determined, and this information does not form part of the common general knowledge in the art, the specification does not provide an enabling disclosure of the invention claimed (Minnesota Mining & Manufacturing Co’s (Suspension Aerosol Formulation) Patent [1999] RPC 135).

Undue burden

Jump back to Examination practice - Undue burden

The disclosure of an invention is not incomplete merely because a reasonable degree of difficulty is experienced in its performance. In seeking to perform the invention, the person skilled in the art may carry out ‘routine trials’ and ‘normal routine matters that they would seek to do and be able to do’ (that is, ordinary methods of trial and error which involve no inventive step). These are generally necessary in applying the teachings of a specification to produce a practical result. However, it would be an undue burden if the person skilled in the art had to undertake prolonged research, enquiry or experiment, or take an inventive step in order to carry out the invention as claimed (Eli Lilly & Co. v Human Genome Sciences, Inc. (2008) EWHC 1903 (Pat); (2008) RPC 29 at paragraph 241).

Considering undue burden

In considering undue burden, examiners should have regard to the nature of the invention and the abilities of the skilled person. They can then ask whether the specification requires the skilled person to carry out tests or developments that go beyond the routine (Eli Lilly & Co. v Human Genome Sciences, Inc. (2008) EWHC 1903 (Pat); (2008) RPC 29 at paragraph 241 and Halliburton Energy Services Inc. v Smith International (North Sea) Ltd (2006) RPC 2).

Where the invention involves a new principle of general application and the claimed technique has broad applicability, if the specification provides an enabling disclosure of one practical application of the principle, implementation of the principle for an alternative application may not involve an undue burden. However, this will depend on the facts of the case and be influenced by the extent to which the information in the specification could be used to develop further embodiments without a major conceptual leap (Kirin Amgen/Erythropoietin II T 636/97 at section 4.5).

The degree of skill or knowledge to be expected of the person skilled in the relevant art will naturally depend on the complexity of the art in question. Where the art is especially complicated and difficult, it is inappropriate to consider the skilled person to be a worker on the shop floor. Nevertheless, this hypothetical addressee is not a person of exceptional skill and knowledge and is not expected to exercise any invention or conduct any prolonged research, inquiry or experiment. They must, however, be prepared to display a reasonable degree of skill and common knowledge of the art in making trials and to correct obvious errors in the specification if a means of correcting them can readily be found (Valensi & Another v British Radio Corporation (1973) RPC 337).

See also Catnic Components Limited v Hill & Smith Limited (1982) RPC 183.

Errors or omissions

If there are actual errors or omissions in the specification, the specification will not provide a clear enough and complete enough disclosure unless the person skilled in the art would recognise that there was an error or omission and could rectify this without further invention (Eli Lilly and Co v Human Genome Sciences, Inc. (2008) RPC 29 at page 241 referring to Valensi v British Radio Corporation (1973) RPC 337).​​​​​​​

Cyclic inventions

As a general rule, one specification cannot be used to assist in the interpretation of another, even if both are filed by the same applicant (Pfizer Inc v Commissioner of Patents (2005) FCA 137). The fact that one specification contradicts the other is not a basis for an objection, as each application stands on its own. Instead, examiners should raise an objection of lack of clear enough and complete enough disclosure in relation to both applications and seek clarification from the applicant(s).

Claims as the basis of disclosure

When assessing compliance with s.40(2)(a), the specification must be read as a whole. Therefore, the claims in the specification can be used to dispel ambiguity or uncertainty concerning the description of the invention. This principle was provided in the context of full description in Kimberly-Clark v Arico (2001) 207 CLR 1 at pages 12 and 13. However, it would also apply to the assessment of clear enough and complete enough disclosure (see also Pfizer Overseas Pharmaceuticals v Eli Lilly and Company (2005) FCAFC 224 at paragraph 325).

Amended Reasons

Amended Reason Date Amended

Published for testing
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