European (EPO) patent applications

This page explains some of the issues and practices relating to European (EPO) patent applications.

Filing considerations
We often amend patent applications prior to filing with the European Patent Office (EPO) to minimise the chances of there being problems in meeting the EPO’s requirements during prosecution. How much we can amend the application depends on whether the application is a “convention” filing or a Patent Cooperation Treaty (PCT) regional phase entry. This is because we have the option of making amendments that introduce new subject matter when making Paris Convention filings and so we have a free hand to make changes that address EPO requirements. This is not the case for PCT regional phase entries where we cannot add subject matter over the disclosure of the PCT application and so we are constrained in the amendments we can make.

One consideration that prompts amendments is minimising the official fees that are payable to the EPO upon filing or shortly thereafter. The EPO’s official filing fee contains an element that penalises lengthy patent applications. An additional EUR17 (as of January 2025) is charged for every page over 35 pages and the total number of pages is calculated by adding the description pages, claims pages, drawing pages and abstract page. Of greater significance is the EPO’s additional claims fee. As of January 2025, the fee is EUR275 for every claim in excess of 15 and up to 50 and EUR685 for every claim in excess of 50. The additional claims fee may be deferred for around six months or so for PCT applications entering the European regional phase.

Prosecution issues
The EPO issues a search report that is accompanied by a search opinion. The search opinion provides reasoned objections to why the application is not allowable for grant or indicates that the application is in order for grant.

The patent application and search report are published at the usual time of 18 months from the filing date (or priority date, if claimed). If the search report is delayed, this will be published separately once available. Publication of the search report sets a six-month period for paying the examination and designation fees. For PCT regional phase entries, it is publication of the PCT application in the international phase that counts and so, generally, the fees are due upon filing or soon after. A single designation fee must be paid that covers all contracting states and there is the option to pay individual fees for each extension and/or validation states wanted by the applicant.

During examination, the EPO will look to see whether the application meets the requirements of the European Patent Convention (EPC). The EPC is the EPO’s implementation of harmonised patent law from around the world. However, the EPO has some flexibility in how the broader legal framework is interpreted and implemented. The following sub-sections explain some issues specific to the EPO.

What constitutes “prior art”
For a patent to be granted, the claims must define an invention that is novel and not obvious over the “prior art”. In common with standard practice, the EPO considers any public disclosure made before the filing date of a patent application to constitute prior art (or any disclosure before the priority date if there is a priority claim). The prior art cited by patent offices is mostly other patent applications, although academic publications are also frequently cited.

Patent applications typically do not publish until 18 months after filing. Consequently, situations arise where European patent applications for the same invention are filed such that the earlier application is not published until after the later application has been filed. Under the definition of prior art given above, the later application would not lack novelty over the earlier application and so two European patents for the same invention could arise.

The EPO avoid this situation by considering such earlier-filed but later-published applications when assessing novelty. However, the EPO will not consider such earlier-filed/later-published European applications when assessing whether a claim is obvious (i.e. whether the claim possesses the required inventive step). This allows us to overcome such earlier-filed and later-published applications by introducing a trivial feature into the claim that would not provide an inventive step but that does provide the required novelty.

How inventive step is assessed
In common with most other patent offices, the EPO considers an invention to involve an inventive step if it would not have been obvious to a “person skilled in the art” when judged against the closest prior art. The EPO implement this using a “problem and solution” approach. In summary, they try to identify a technical solution to a technical problem that would not have been obvious to the skilled person. In more detail, the approach should follow these steps:

1. Identify the closest prior art

The closest prior art is usually the disclosure with the most features in common with the particular claim under consideration. However, the choice can be influenced by other factors like whether the prior art is directed towards a similar purpose as the claimed invention or at least belongs to the same or a closely related technical field.

2. Determine the differences between the closest prior art and the claimed invention This is essentially the test for novelty and sees all the novel features of the claimed invention identified.

3. Establish the technical effect resulting from the novel features The technical effect may relate to an advantage associated with the novel features of the invention or may be that the invention provides an alternative way of achieving the same technical effect as is obtained by the closest prior art. Notably, the effect must be ‘technical’ such that features relating to excluded subject matter cannot contribute to inventive step (e.g. business method steps).

4. Formulate the objective technical problem to be solved The EPO will then formulate a technical problem that is solved as a result of the technical effect identified. Importantly, the objective technical problem must be formulated so as not to contain pointers to the technical solution because this would amount to impermissible hindsight. For example, the technical problem might be how to provide an alternative way of achieving the same technical result as the closest prior art.

5. Consider whether or not the claimed invention, when starting from the closest prior art and the objective technical problem, would have been obvious to the person skilled in the art.

The skilled person is assumed to possess no ingenuity whatsoever and can only provide progress in the field by seeing what follows plainly from the prior art when trying to solve the objective technical problem. Anything that follows logically from the prior art is therefore considered “obvious” to the skilled person. If the merest spark of imagination is required to arrive at the claimed invention, it should be considered to have the requisite inventive step.

Most commonly, a lack of inventive step is demonstrated by combining prior art documents. The EPO must show that the skilled person would have combined the two prior art disclosures to arrive at the claimed invention: it is not enough to show that the skilled person could have done so. If the technical effect of an invention is surprising or unexpected, it is less likely that the claimed invention will be considered obvious.

In most circumstances, only two prior art documents can be combined when raising an inventive step objection – “mosaicking” many documents is not allowed. There is an exception where the novel features of the claimed invention form separate groups not linked so as to solve a single technical problem. In this case, the EPO can raise “partial problems”, i.e. different problems associated with different novel features. Then, a single closest prior art document must be chosen but a different prior art document may be added to solve each of the partial problems.

Two-part form for independent claims
An EPO examiner will typically object if a European patent application does not present the independent claims in “two-part form” with a preamble that lists features to be found in the closest prior art followed by a characterising portion that lists features novel over the closest prior art. The preamble and characterising portions are separated by the either “characterised in that” or
“characterised by”.

Although EPO examiners will almost always request two-part form, it is not always necessary. The requirement may be overlooked where we can show that two-part form is inappropriate, for example because it would give a misleading picture of the invention or of the prior art.

Added subject matter
Patent law is harmonised to the extent that any amendment of a patent application after filing must not add subject matter to what was disclosed in the application as filed. The EPO is particularly strict in how it applies this requirement.

The EPO’s gold standard requires the subject matter of any amendment to be clearly and unambiguously disclosed in the application as filed. To assist the EPO examiner, we are required to indicate the passage in the as-filed application that provides basis for any amendment. The examiner will then look at that passage to identify the features included in the amendment and to ensure those features have not been cherry-picked from a disclosure of a combination of other features. The examiner will also consider other passages when deciding this. If the examiner believes that not all features from a disclosed combination have been included in a claim amendment, the examiner will object that the amendment amounts to “an intermediate generalisation”.

By way of example, consider a claim amendment to specify “wherein the component furthercomprises A, B and C.” If the basis indicated is a sentence saying, “The component may also include
A, B, C, D and E”, then the amendment is an intermediate generalisation: features A, B and C have been isolated from features D and E. Even if the basis says, “The component may also include A, B and C”, indicating this sentence alone will not be enough if the following sentence says, “Furthermore, A is connected directly to both B and C, while B and C are not directly connected together.” These further requirements must also be included in the amendment.

Further consideration must be given to the overall combination of features created with a claim amendment. If the claims already included features, X, Y and Z, would an amendment to introduce features A, B and C lead to new combinations? This can arise when some claims relate to one embodiment and an amendment is based on the description of another embodiment.

It is important to take into account the EPO’s strict stance on added subject matter when drafting a patent application. Where separable features are described in combination, it is sensible to emphasise that these features can be used in isolation from one other. However, generalised statements that say all or many features are optional also causes problems because the EPO may object to an amendment as attempting to claim a specific combination of features from among many combinations possible. It is better to consider particular combinations of features that may provide useful fallback positions in the claims and to ensure these combinations are described. Ideally, the claims and/or the description should provide a series of fallback positions to provide stepping stones between the broad combination of features set out in an independent claim and the narrow combination of features present in the embodiments described.

Clarity
In common with most patent offices, the EPO enforces a requirement that claims must be clear to ensure certainty for third parties. Specifically, a third party should be able to tell whether they stand to infringe a claim without any doubt.

Various issues can give rise to a lack of clarity, including issues in the claims themselves as well as issues in the description that cast doubt on the scope of the claims. There follows a summary of
some clarity issues frequently raised by the EPO.

• Claims that are not clear from the wording of the claim alone: there should be no need to refer to the description to interpret the meaning of a word or phrase in a claim.
• The presence of vague terms that lack well-defined limits such as thin, strong, near, approximately and substantially.
• Inconsistency between the claims and the description. If the description says that features of an embodiment of the invention are essential, then the EPO will require those features to be present in the independent claims. Conversely, the description should not present features as optional if those features are required by the independent claims.
• References to spirit of the invention or to equivalents of claim features are viewed as casting doubt on the provision in the European Patent Convention that governs claim scope (Article 69 EPC and the associated Protocol).
• Multiple claims in the same category are not allowed (e.g. apparatus or method), although there are a few limited exceptions such as interrelated products (“plug and socket” type arrangements), alternative solutions to the same problem (as opposed to mere recasting of the same solution in alternative wording) and different uses of the same product or
  apparatus.
• The claim category must be clear, so including method steps in an apparatus claim should be avoided. Instead, the claims should define the apparatus features that perform the method steps, using language like a motor configured to drive…
• Claims that define a result to be achieved rather than the means for achieving that result. This often arises because of an over-generalisation of the inventive concept so that the claim ends up merely defining the technical problem to be solved instead of generalising the method steps or apparatus features needed to achieve the result.
• The EPO will raise a clarity objection when an apparatus claim defines the apparatus with reference to a non-claimed element where knowledge of the unclaimed element is required to determine the scope of the claim. The key issue is that it must be possible for a third party to determine whether an alleged infringing product falls within the scope of a claim from examining the claimed product alone.

Examining Division Oral Proceedings
If agreement on an allowable set of the claims cannot be reached with the EPO in writing, the EPO may summon the applicant or their representative to oral proceedings. In most cases, this hearing provides an applicant with a final opportunity to present its case to avoid refusal of the application.

The summons will set out the outstanding objections to be discussed at the oral proceedings and will set a deadline for filing written submissions (usually one month before the oral proceedings). Written submissions may provide further arguments and/or amendments, including multiple sets of amended claims to provide further fall-back positions. The oral proceedings will be cancelled if the EPO examiners find at least some of the arguments/amendments persuasive.

Generally, the hearing will be conducted via video conference although some oral proceedings take place in person at one of the EPO’s offices. The EPO will be represented by the primary examiner already responsible for the application along with two further examiners from the same examining division. Under certain circumstances, the applicant and/or representative may be accompanied by others such as an inventor or expert witness. The EPO’s decision on whether to allow or refuse the application is announced at the end of the hearing and later confirmed in an official written communication. If the decision is adverse to the applicant, the decision may be appealed to an independent board of appeal.

Grant issues
Before grant, the EPO issues a communication proposing a text of the patent specification for the approval of the applicant and inviting the other formalities required for grant to be performed. These formalities include paying the official grant fee and filing translations of the claims into the other two official languages of the EPO (so that the patent may publish with claims provided in English, French and German).

Once these formalities have been met, the patent will grant and the EPO will publish a mention of the grant. The patent must then be brought into effect in those countries required by the patentee. The requirements for doing so vary from state to state and may require any of the following: filing a translation of the claims, filing a translation of the description, appointing a local representative and paying a fee. Generally, the time limit for doing so is three months from publication of mention of grant. Some countries have no additional requirements and so the European patent has immediate effect once the mention of grant is published.

Post-grant issues
While grant of a patent generally sees responsibility for the patent transfer from the EPO to the national offices in which the patent is validated, an exception is opposition proceedings. Publication of the mention of grant starts a nine-month period in which anyone can file an opposition to the grant of the patent. Parties accused of infringing a patent can also join a pending opposition against the patent after the nine-month opposition period. A written notice of opposition is required in which the opponent must argue why the patent is invalid and provide supporting evidence where required (e.g. prior art to support an argument that one or more claims lack novelty or inventive step).

The opponent is provided with an opportunity to respond in writing, with counterarguments and/or amendments to the patent. An EPO opposition division will decide on the issues, based on the written submissions and, in most cases, after hearing the patentee and opponent(s) present their arguments at oral proceedings. The opposition division can maintain the patent as granted, maintain the patent in amended form or revoke the patent in its entirety. Maintaining the patent has no effect on the validated parts of the patent. Maintaining the patent in amended form requires the EPO to republish the amended patent along with translations of the amended claims. Further translations may also be required for the validated patents, depending on the requirements of each individual state. The decision of the opposition division is open to appeal by any party adversely affected.