Sufficiency of description and drafting rules

TheA83 CBE has:

The invention must be disclosed in the European patent application sufficiently clearly and completely for a person skilled in the art to perform it.


Sufficient description

Appreciation date

The sufficiency of description, to assess the validity of a patent / application, is assessed on the filing date of the application (Guidelines F-II 4.1).

In order to know if a disclosure anticipates an invention, the assessment of the sufficiency of the description is different: it is on the date of publication of this disclosure that it is necessary to place (or deposit for a document A54 (3) EPC) (T206 / 83, T26 / 85 and G-VI Guidelines 4).

Assessment criteria

The sufficiency of description is appreciated in relation toGuidelines F-II 4.1):

  • to general knowledge basic of the skilled person;
  • to the invention described in the application;
  • the documents cited.

If products are claimed, only their manufacture must be sufficiently described (T866 / 00): it is not useful to describe their use.

Description adequacy checks

In order to verify that the description is sufficient for the implementation of the invention, the Boards of Appeal proposed a 4-step test (T593 / 09, T2403 / 11):

  1. Identification of the problem solved by the invention;
  2. Is the characteristic that is not sufficiently described (eg threshold of porosity of a material) to solve this problem?
  3. Is there any ambiguity in the measurement / estimation of this characteristic?
    • ex. several measurement methods give different results, depending on the conditions the measurements are different (T2096 / 12) ; 
    • a measurement via a specific machine is mentioned in the description but this machine is no longer manufactured (T1293 / 13) and it is impossible to know if the new machines give the same result; 
  4. Is the ambiguity such that the invention is not sufficiently described? (eg discrimination of satisfactory materials the technical problem is not possible).

Once this test is done, it becomes possible to determine if the invention is insufficiently described.

Parameter measurement case

It should be noted that inaccuracies in the measurement of a parameter or the existence of several measurement methods do not necessarily lead to a lack of description (T608 / 07T1768 / 15) but often with problems of clarity.

Nevertheless, in a case where the parameter is crucial to solve the problem underlying the invention, the measurement method must give coherent values so that the person skilled in the art knows, when reproducing the invention. if what it produces solves the problem or not (T815 / 07, T1305 / 15): it is then a problem of sufficiency of description.

Case of neural networks

In the case of an invention using a neural network, we can ask ourselves whether it is useful / necessary to describe how the neural network has been trained.

This is all the more relevant as the training of networks requires several megabytes (see gigabytes) and that it is not really possible to include its data in the text of the request.

According to case law (T161 / 18), the simple fact of indicating in general that the training data should cover a wide scope (eg patient age, sex, etc.) is not sufficient.

It is likely that it will be necessary to specify precisely which data types and which parameters / hyper-parameters are used. But to what extent, it is a real question ...

Embodiments described

Wider claim than the modes described


According to some decisions, the presentation must be sufficient to allow the implementation almost all the modes covered by the claim (T409 / 91).

Nevertheless, other decisions consider that the criterion of the sufficiency of the description is fulfilled if at least one embodiment is described (T292 / 85 or T389 / 94).

It is therefore necessary to look at the facts: if the invention is very innovative, it can often be easily generalized once the person skilled in the art has been guided to an embodiment (Directives F-III 1).

Thus, it will be easier to accept the description of a single embodiment if the invention is innovative (Directives F-III 1).

It is appropriate to admit gropings to a limited extent, for example in the case of an unexplored area or where many technical difficultiesT292 / 85, T409 / 91 and Directives F-III 1)..

A broad claim may be admissible if it is possible to extend the examples given by usual experimental or analytical methods (Directives F-IV 6.3).

“Prohibited area” of a masked clarity claim or objection

It may happen that a characteristic is so unclear that the person skilled in the art is unable to know whether or not he is working in the claimed field ("forbidden domain").

Many opponents have often tried to argue that this is a problem of sufficiency of description (clarity is not a ground of opposition).

But today, the boards of appeal are quite unanimous: the definition of the claimed area was a question ofA84 CBE more thanA83 CBE (T1811 / 13).

It must be ensured that an objection of insufficiency of description arising from an ambiguity is not a mere objection of clarity made up (T608 / 07, 2.5.2).

Mode of operation or area of operation…

… Not working within the full scope of the claim
Burden of proof

If it is argued that, in accordance with the details given in the description, some areas or embodiments do not work, the party raising the problem must provide the elements supporting its position (ie serious reservations, supported by verifiable facts, T409 / 91 and T694 / 92).

Nevertheless, no proof is required from the person who questions the operation. The burden of proof of good functioning rests with the applicant / holder (Guidelines F-III 4).

However, this does not mean that, as soon as an area covered by the claim does not work, there is insufficient description. Indeed, when it is clear to those skilled in the art that such an area is not reasonable, there is no problem (T1943 / 15).

Sufficiency objection of description

If a claim covers several modes and some do not work, the claim will have to be considered as insufficiently described even if the other modes work correctly (T1173 / 00, T239 / 13).

Alternative to this objection

An objection relating to the absence of an industrial character (A52 (1) EPC) can also be raised (Guidelines F-III 3).

… No longer working

It may happen that an embodiment can no longer be implemented.

This happens when the latter is so precise, that a special machine is needed to operate it and this machine no longer exists (e.g. energy of a measured shock using the Drop-Weight Tester RTD-5000 from Rheometrics, Inc., T1714 / 15).

In this case, we have a problem of sufficient description.

… Not always working (linked to chance)

It may happen that the proper execution of the invention depends on chance (Guidelines F-III 3).

Thus, the details given in the description do not systematically make it possible to obtain the desired result (Guidelines F-III 3):

  • electronic chip manufacturing;
  • microbiological process involving mutations;
  • etc.

These inventions will be considered sufficiently described only if (Guidelines F-III 3):

  • satisfactory results can be obtained repeatedly, even if there are failures; and
  • whether it is possible to know if the result is satisfactory using non-destructive testing methods.
… Not always working (reliability lower than 100%)

Some mechanical devices may not have absolute reliability (eg mechanical sorting device).

Therefore, a person skilled in the art must endeavor to demonstrate a constructive and non-destructive spirit in order to arrive at an interpretation of the claim that is technically meaningful and takes into account the whole of the description of the invention contained in the patent (T383 / 14).

Thus, even if a mechanical sorting machine occasionally makes sorting errors, the invention will be considered sufficiently described.

… Difficult to achieve or imperfect

The difficulty of realizing an invention does not necessarily mean that the invention is insufficiently described (Directives F-III 5.3).

Thus, an embodiment that does not function perfectly (eg electrical switch allowing a slight residual current to pass through, open) and renders certain applications of the invention inoperative only in certain cases (eg electrical circuit requiring an absolutely zero current when the opening of the switch) will be considered sufficiently described (Directives F-III 5.3).

… Not making it possible to resolve the technical problem

If the invention does not make it possible to obtain the alleged technical effect, it is not possible to reject the application for lack of description. that if this technical effect is claimed (G1 / 03point 2.5.2 or T2001 / 12).

Nevertheless, if the fact of not reaching the technical effect is bound (T2001 / 12):

  • the absence of an essential feature, an objection of clarity may be raised;
  • the technical impossibility of arriving at the effect with regard to the assertions of the prior art, an objection of inventive activity can be raised.

We can summarize the decision as follows G1 / 03, point 2.5.2:

Embodiments not working
… Citing brands, proper names, trade names

Indeed, these terms are simply an indication of origin and can refer to a whole range of different products.

To be sufficiently described, the product must be sufficiently identified, without reference to any mark, proper name or commercial name, to allow the realization of the invention, unless these terms have a precise meaning for those skilled in the art ( eg cable ' Bowden »Washer« Beautiful city " , closed off " Panhard »Caterpillar« Caterpillar") (Guidelines F-III 7).

If a product of a mark is mentioned but the composition and manufacturing method of the product is secret, it is highly likely that the requirement of sufficient description is not met (T797 / 14).

Number of embodiments described

The description must include, at least, the description of an embodiment covered by the claims (Directives F-III 1), this working embodiment (see above, Guidelines F-III 5.1).

If an embodiment may be sufficient, it may be wise to give several, especially if the wording of the claims is rather broad and the general knowledge of those skilled in the art is not sufficient to extrapolate the embodiment of embodiments not described but covered (T727 / 95) by the claims.

Non “classic” method

When the applicant chooses to use non-standard methods (eg measurements), it is particularly important to detail them in order to ensure that these methods are sufficiently described (T602 / 10).

Incorporation by reference

An application will not be insufficiently described if an essential element of the description is mentioned by reference only without being reproduced in extenso.

The language of the document cited does not matter (T920 / 92).

The reference will be valid if (HV directives 2.5 together H-IV Guidelines 2.3.1):

  • at the filing date, a copy of this document was available to the EPO (which is the case if it is another European patent application, T737 / 90);
  • at the date of publication, this document was publicly available (T426 / 96).

Burden of proof

If the Examining Division establishes, with reasons, that the invention is not clearly and fully disclosed, it is up to the applicant to demonstrate that the invention can be implemented and reproduced in virtually any claimed area (Directives F-III 1).


In case of insufficient description, the claims should be limited in order to exclude the inadequately described embodiments (Guidelines F-III 2).

Moreover, it is impossible, after the filing, to add in the request the missing description in order to "render" the invention sufficiently described: indeed, such a modification would be contrary to the article A123 (2) EPC.

Description writing rules


The R42 EPC precisely defines the rules to which the description must comply.

This rule aims atGuidelines F-II 4.1)

  • to ensure that the patent application includes sufficient technical information for a person skilled in the art to perform the invention as claimed,
  • to allow the person reading the presentation of the invention to understand the contribution made to the state of the art by the invention as claimed.

State of the art

If the search report reveals relevant documents, a reference to these documents may be required (R42 (1) (b) EPC) and a brief summary.

This introduction a posteriori does not contraveneA123 (2) EPC (T11 / 82).

If the Examiner requires a reference to be made, this requirement must be met or the application will be rejected (A97 (2) EPC) or revocation of the patent (A101 (3) (b) EPC).

If a prior art is A54 (3) EPCit is useful to mention it in the application (Guidelines F-II 4.3).

Technical problem and solutions

The R42 (1) (c) EPC asks that it is possible to deduct the technical problem of demand.

The statement of the problem should not include disparaging statements (Guidelines F-II 4.5).

It is possible to write this solution with reference to the claims: "This problem is solved by the device of claim 1" (this is not possible in France).

Description of at least one embodiment

It is appropriate to look at the chapter on the sufficiency of description concerning this description (R42 (1) (e) EPC).

A simple copy and paste of a computer program is not enough to fulfill this condition (Directives F-II 4.12) even if it is possible to illustrate the invention.

Industrial application

Most often this industrial application (R42 (1) (f) EPC) is deduced directly from the request and it is not necessary to state it explicitly.

If it is not obvious (eg test method), it must be made explicit (Guidelines F-II 4.9).

Its mention is obligatory for an invention relating to a gene sequence (R29 (3) EPC).

Incorporation by reference


It is possible to include in a claim a characteristic present in a document cited in the application, if it is obvious that this document forms part of the invention for which protection is sought (T6 / 84).

The language of the quote does not matter (T920 / 92).

A123 (2) EPC

Therefore, if this incorporation by reference is essential for the invention, the applicant will have to explicitly include these characteristics in the description (Directives F-III 8).

So that this integration is not contrary to A123 (2) EPC, it is necessary (HV directives 2.5, T689 / 90):

  • protection is or could be sought for those characteristics;
  • whereas such characteristics contribute to the achievement of the technical objective pursued by the invention and are therefore part of the solution of the technical problem underlying the invention claimed in the application;
  • that such characteristics are obviously implicitly included in the description of the invention which must be included in the application at the time of filing (A78 (1) (b) EPC), and therefore form part of the content of the application as filed (A123 (2) EPC);
  • that said characteristics are precisely defined and can be identified among all the technical information contained in the reference document.

The only quotation of a document is not a priori sufficient (T276 / 99). On the other hand, the indication "the polymer of the document D1 is advantageous" is sufficiently precise.

Public availability of the reference

The reference will be valid if (HV directives 2.5 together H-IV Guidelines 2.3.1):

  • at the filing date, a copy of this document was available to the EPO (which is the case if it is another European patent application, T737 / 90);
  • at the date of publication, this document was publicly available (T426 / 96).

Prohibited items

The description must not contain (R48 (1) EPC):

  • elements contrary to public order;
  • derogatory statements;
  • foreign or superfluous elements.

The deposit section verifies these conditions (A90 (3) EPC) and omits these elements in the publication of the application (Directives A-III 8.1).

If such elements are only found at the examination stage, the Examining Division will request their deletion (Guidelines F-II 7.5).

Deposit of biological material


This theme is addressed here because, even though it is not exactly part of the description, the deposition of biological material is a key element for the sufficiency of description.

Definition of biological material

We speak of biological matter when this matter (R26 (3) EPC):

  • contains genetic information;
  • and is, in a biological system:
    • self-reproducible or
    • reproducible.

Conditions to be fulfilled


In order to fulfill the requirement of sufficiency of description, it is necessary:

  • one sample of the biological material was deposited from an authorized depositary authority (R31 (1) (a) EPC):
    • cf. Budapest Treaty of April 28, 1977;
    • no later than the filing date of the application (to allow the Examiner access to it, Directives F-III 6.2);
    • the authorized depositary authorities (about 40) are mentioned (" 4.2 International Depositary Authorities under Article 7 of the Budapest Treaty », OG 2012, 324, II.1.4 and I.4.2):
  • that demand contains the relevant information the applicant has on the characteristics of the biological material (R31 (1) (b) EPC). In general, this relevant information is (Directives F-III 6.3):
    • the classification of the biological material (eg for bacteria, the literature relevant to the classification will be RE Buchanan, NE Gibbons: Bergey's Manual of Determinative Bacteriology);
    • significant differences from known biological materials;
    • morphological and biochemical characteristics, to the extent that the applicant has this information;
      • information useful for the recognition and reproduction or multiplication of biological material, eg appropriate media (ingredient composition));
    • the proposed taxonomic description, to the extent that the applicant has this information;
    • if the deposited biological material can not reproduce itself but must be reproduced in a biological system (eg viruses or free RNA), the above information for that biological system (possibly associated with a this biological system);
  • for the deposited biological material,
  • if the biological material has been deposited by a person other than the applicant, that is provided (R31 (1) (d) EPC);
    • the name and address of the applicant
    • a document proving that the applicant
      • authorized the applicant to refer in the application to the biological material deposited and
      • has unreservedly and irrevocably consented to make the material available to the public.

However, simply depositing a biological material can not constitute a patent application per se (T418 / 89).

Referral to a previous application

Where an application is made by reference to a previous application, the following conditions are deemed to be met on the filing date to the extent that the application was filed on the filing date of the earlier application (Guidelines A-IV 4.1.2):

  • relevant information available to the applicant on the characteristics of the biological material (R31 (1) (b) EPC);
  • indication of the depositing authority of the deposited biological material (R31 (1) (c) EPC);
  • indication of the serial number of the deposited biological material (R31 (1) (c) EPC).



The Receiving Section checks, when examining certain irregularities (A90 (3) EPC), if the application meets the requirements of R31 (1) (c) EPC and R31 (1) (d) EPC (Directives A-III 1.2 iv).

If the Receiving Section finds that the information is missing, it shall inform the applicant (Directives A-IV 4.2).

Deadline for correction

The deadline for correcting this irregularity is (R31 (2) EPC, min the following deadlines):

  • 16 months from the priority (or at least before the end of technical preparations for publication);
  • before any request for advance publication according to A93 (1) (b) EPC ;
  • 1 month after notification of the applicant that a third party may consult the record, because an action has been brought against him (A128 (2) EPC).

TheA122 EPC is applicable.

This period therefore does not run from the notification indicating the irregularity.

If ever the information from the R31 (1) (c) EPC and R31 (1) (d) EPC are provided afterwards, the application will be insufficiently described (Directives F-III 6.3) even though they would be provided after:

  • via a correction of the R56 EPC,
  • through the provision of an earlier application to which reference is made in accordance with R40 EPC.

Rejection of the request

If a provision of the R31 (1) EPC is not complied with, the sufficiency of description is not satisfied and the application is rejected under theA97 (2) EPC (Directives F-III 6.3).

In this case, the loss of right occurs upon filing (even if a filing date is assigned).

Thus, even if the application is rejected, the priority of this first application can be validly claimed by a second request. if and only if for this first application, a sample was submitted no later than the filing date of the first application (ie R31 (1) (a) EPC was respected) by application of A88 (4) EPC (T193 / 95).

Access to biological material


Normally, from the publication of the patent application, the biological material is accessible to any person who requests it (or before a third party if an action is brought against this third party according to A128 (2) EPC) (R33 (1) EPC):

  • if the applicant has requested it before the end of the technical preparations for publication (R32 (1) EPC):
    • a sample is given to an expert if the access request is made:
      • before publication of the mention of the grant (R32 (1) (a) EPC);
      • before the expiry of a 20 years from the time of filing if the application is rejected / withdrawn / deemed withdrawn (R32 (1) (b) EPC);
    • the experts can be:
      • any natural person designated the person wishing to access the biological material, if he proves during this access request that the applicant agrees (R32 (2) (a) EPC);
      • a person approved by the President of the EPO (less than 20 experts who have not changed since 1992, list in " 1.5 Microbiology experts approved by the President of the EPO in accordance with Rule 32 (2) (b) EPC », OG 2012, 324 which refers to " List of experts approved for the purposes of R28 EPC », OJ 1992, 470) (R32 (2) (b) EPC);
  • if not,
    • a sample is then given directly to this person.

Restriction on use

Nevertheless, the person who has access to this subject must commit to (R33 (2) EPC) (until the patent is extinguished in all States or until the application is rejected / withdrawn / deemed withdrawn):

  • do not communicate it to a third party (even in a derivative way):
    • unless the applicant so permits,
    • unless the material derived therefrom is communicated for the purpose of depositing biological material (R33 (3) EPC) for a patent proceeding;
  • to use it only for experimental purposes:
    • unless the applicant so permits;
    • unless that person has a compulsory license.

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