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Inside the mind of an EPO examiner

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Copyright © DrugPatentWatch. Originally published at Inside the mind of an EPO examiner

This article was originally published by Philippe Lahorte in World Patent Information
Volume 54, Supplement, September 2018, Pages S18-S22 Under a Creative Commons license.


This article provides an insight into the thinking of EPO examiners during the search process and how examiners balance high quality with service and efficiency.

At the basis for high-quality search and examination lies the consistent and transparent application of the legal concepts and procedures defined by and following the European Patent Convention (EPC). This article addresses the key questions how examiners come to an understanding of the invention and how they dissect the claims and develop search and examination strategies.

Finally, this article illustrates that – like other highly specialized knowledge workers – the job of a patent examiner is highly complex and entails many challenges. Experienced examiners not only apply their technical and legal expertise. They also exercise sound judgment and decision-making skills, work strategically and adopt a strong service orientation.

1. Introduction

Comparable to other knowledge workers such as surgeons, pilots or lawyers, the profession of a patent examiner builds on specialist knowledge acquired through academic education complemented by several years of professional training. Contrary to a doctor or pilot however, the job and role of a patent examiner are generally less well known. Undoubtedly, this is related to the highly specialized nature of the intellectual property world in which they operate [1] and the specific role they perform in it – searching and examining patent applications and granting (or refusing) patents.

On a professional level patent examiners mainly interact with patent attorneys, which represent patent applicants. Patent examiners apply the patent law in accordance with relevant guidelines and jurisprudence. Both the applicable law and its interpretation are public and transparent and hence a consistent behaviour and outcome can be expected. The legal frameworks and guidelines that define the role and responsibilities of the EPO examiners are respectively the European Patent Convention and the Guidelines for Examination in the EPO. In addition, examiners will observe relevant case law of the EPO’s Boards of Appeal.

The aim of the present article however is to provide a general and non-legal perspective on how patent examiners at the European Patent Office work in practice. The focus is put on the search process: How do they come to an understanding of the inventions in front of them? What are their considerations in the search and examination process? And last but not least, as civil servants, how do they balance quality, service and efficiency?

This article will correspondingly also provide insight into the many soft issues, constraints and challenges facing examiners, as knowledge workers at intersection of technology, prior art searching and intellectual property law.

The broad aim of the present work is to increase the understanding of the work and role of EPO examiners, the consistency and predictability of their actions, and the transparency of the EPO’s search and examination procedure.

This helicopter view on the examiners’ profession might be of interest to several target groups: firstly, the strategies and considerations that are at the core of the search processes of EPO examiners might be beneficial to patent information professionals and users of patent databases, either in their own prior art searches or in the development of patent information products and services (e.g. databases and analytic tools). Secondly, all patent examination related aspects may be helpful for patent applicants and their professional representatives in drafting and prosecuting applications and interacting with examiners. Finally, for those generally interested in the patent examiners profession, or contemplating a career as examiner, this paper will give a flavour of a key facet in the working life of an EPO examiner.

2. The EPO patent examiner corps

On a total of about 7000 staff, the EPO employs about 4300 patent examiners. These are highly qualified engineers and scientists (often PhD qualified with several years of professional experience), recruited from among the 38 member states [2]. They work on patent applications in the EPO’s three official languages (English, French and German) and with time most specialize in a relatively narrow technical field.

All newly recruited examiners participate in the same, 3-year in-house training program, which aims to provide all the specialist knowledge and skills necessary for the examiner’s job. Complementing the classical classroom training, a significant part of the program consists of on-the-job learning and training. Under the supervision of highly experienced coaches, new recruits acquire an in-depth knowledge of the relevant legal aspects and the specific working practices specific to their technical field. Every search and examination report produced by the coachee in the first year is discussed with and revised by the coach. The examiners’ job is a very complex and as a result the first 3–5 years present a very steep learning curve. Most junior colleagues find the regular (almost daily) consultation and cooperation with senior peers as the most effective way of learning and developing their skills. The strong internal culture of informal and continuous knowledge transfer among EPO examiners [3] is a key element towards achieving and maintaining high quality and efficiency both on the individual and organisational level.

With increasing experience, examiners will work with growing confidence and autonomy on files of increasing technical and legal complexity. They will gradually take up opposition work and start acting as chairman of examining or opposition divisions.

Given the large experience and seniority spread of the EPO examiner population (ranging from new recruits up to examiners with more than 30 years of experience), the complexities of the examiner’s job and the highly dynamic nature of the IP world, it should come as no surprise that there is no such thing as the patent examiner.

More realistically, the EPO examiners should be considered as a coherent group of highly educated and trained professionals that are dedicated to consistently apply the law as defined by the EPC and supporting regulations and case law. However, as in any legal profession, the law is indeed being interpreted and applied by individuals, each having their own working style, strengths and experiences.

Therefore, the current article in the first case represents the author’s individual perspective, which he believes is shared by and applies to a large proportion of his peers. Any specific statements in this article regarding working practices should be seen in this context: whatever working style or practice that applies to a highly experienced examiner in one specific technical field, for instance telecommunications or computing, might differ from that of a newly recruited examiner in, for instance, furniture manufacturing or food processing. With this caveat, the author will attempt to describe the EPO examiners’ thinking, constraints and decision taking as specific as possible, and provide context wherever possible.

3. How do examiners come to an understanding of the invention?

Patent applications define inventions in written form. The EPC does not explicitly provide a positive definition of what constitutes an invention. It does however, specify a couple of exceptions. For instance business methods, or discoveries and scientific theories are not considered technical inventions (see Article 52(2) EPC). In general, however, an invention can be considered as a technical solution to a technical problem. Either by serendipity or through research and development, an inventor achieves a novel way of solving a technical problem in a way that is not obvious to a skilled person in that technical field.

The examiner is thus faced with the challenge of trying to understand a specific piece of technology solely based on the specific language and wording the inventor and/or the applicant or his professional representative have used. The examiner does not have the benefit of consulting the inventor, testing results in a laboratory, or inspecting a real specimen of the invention.

Hence, whether, or to what extent, the examiner can come to an understanding of all aspects of the invention in an efficient manner hinges on a clear definition and description of the invention. The quality of the drafting and the typology of the filing strategy are major determinants of the quality of the ensuing search and examination procedure [4], [5], [6], [7]. Suboptimal patent drafting may result when applications are drafted without adequate knowledge of the formal requirements or the legal frameworks (e.g. this might apply to some inventors), or linguistic command of the filing language, translation inaccuracies, etc. Moreover, for cost reasons the specific format of the claims or description may be a compromise solution to cover several jurisdictions (e.g. USA and Europe) without necessarily adopting the best-practice mode or requirements of one particular jurisdiction.

4. Claims, description, or drawings: where to start?

Once the formal requirements are checked and met, the application lands on the desk and in the electronic cupboard of the examiner. Although the full application is available electronically, most examiners will currently still start working with the paper file. Generally, a patent application consists of three relevant parts: claims (at least one), a description, and possibly drawings. The question then arises: which part does the examiner start with?

The large majority of experienced examiners will first consider the claims as these define the subject matter for which protection is sought as well as the extent of protection conferred. An independent claim defines the invention with the minimally number of essential technical features required to carry out the invention. Dependent claims add further preferred technical features that correspondingly narrow the scope of protection.

To come to an understanding of the claims, examiners will consider the following questions:

  1. How many claims are defined?
  2. How many independent claims are defined and what is their category (e.g. product or device, method, use)?
  3. What interdependencies (i.e. tree structures) are defined by the dependent claims? Which specific embodiments (i.e. combination of technical features), and how many embodiments, are defined?
  4. For each claim, and starting from the independent claims, which structural technical features are defined? How, do these structural features functionally interact with each other?

As an analogy one could say that the claims are dissected with surgical precision to determine both the anatomy and physiology of the invention that they define.

This process, also known as construing the claims, is performed to determine the broadest possible scope of protection (as defined by the independent claims), all viable fall-back positions for the applicant (these could be defined in the dependent claims, the description or the drawings), and all possible embodiments covered by the wording of the claims [8]. It constitutes the first, and crucial, intellectual contribution performed by the examiner.

As part of this process, examiners will already at this stage attempt to identify potential legal objections to the claims:

  1. Are the claims clear and concise?
  2. In case of amended claims, is there any added subject matter?
  3. In case of multiple independent claims, do the claims define multiple inventions, possibly in a non-unitary manner?
  4. Do the claims define inventions that are excluded from patentability (e.g. medical methods, specific areas in biotechnology, inventions that go against the ordre publique)?

In addition, experienced examiners might already know at this stage, based on their experience and knowledge of the field and prior art, that for instance the independent claim is neither new nor inventive.

The above long and non-exhaustive list of requirements gives a first impression of the many requirements that a good set of claims – and more generally, the complete patent application – need to fulfil: capture the essence of the invention, with an appropriate number of technical alternatives and examples, in wording that is clear (at least to the skilled person, patent practitioner or a judge), and in a format and structure that allows a smooth processing by the patent office. It can be argued that finding the right balance in patent drafting requires extensive technical and legal craftsmanship and a hint of artistry [8], [9].

A less experienced examiner might be tempted to read the description as he would read a scientific article. Experienced examiners often follow a different approach. An experienced examiner has an in-depth knowledge of and expertise in the specific technical field of the invention. Hence, he is familiar with the developments and problems in the field, the specific terminology and jargon used, and the most active players and contributors. Rather than linearly processing the description, the examiner is likely to strategically scan the description in search of answers to the following questions:

  1. Having construed the claims, do I have a correct understanding of the technical problem solved by the invention?

As mentioned above, an invention solves a technical problem. Having a correct understanding of the technical problems faced and overcome by the applicant is crucial for a correct appreciation of the merits of the invention and to subsequently guide the search strategy.

2. Does the applicant acknowledge any relevant prior art in the description?

Any prior art mentioned or discussed in the description might provide a good starting point for the subsequent search. Also, cited prior art may provide valuable pointers towards technically relevant patent classes, keywords or concepts. The examiner might want to feed this information might into the search strategy.

3. Are any specific technical features mentioned in the description that are not contained in the claims?

It is possible that specific preferred embodiments, examples or technical details are exclusively mentioned in the description. The applicant may resort to any of these technical features later in the examination stage to limit the claims. For the search to be complete and efficient, it is therefore crucial that these features are identified right at the start so that they may be in incorporated into the search process.

Finally, figures may further complement the description and contribute in increasing the understanding by visualizing specific embodiments of the invention. Similarly to the description, also the figures may contain unique technical content that is not contained in the claims and that might constitute valuable fall-back positions for the applicant in the examination process. For these reasons the description and figures are often treated in parallel by the examiner.

5. Strategy: how to craft and structure a search

Patents are all about products, devices and processes that are the concrete results of advancements in science and technology. Searching patents however, is not a scientific process in the strict sense of the word. Patent examiners rely on their technical expertise in particular field, their knowledge of the relevant patent laws, their understanding of databases and classification systems, and – last but not least – their mastery of powerful and elaborate search tools, queries and algorithms.

A high performing examiner develops the skill to prioritise and combine these different dimensions depending on the file’s subject matter and to craft this into a search strategy and report that is specifically adapted to the application under study. In other words, the intellectual steps and building blocks composing the search process are unique to the application. In this sense, every search and the resulting search and examination report constitute a highly customised and tailor-made process and service.

In practice, a first step in designing a search strategy consists of codifying all the relevant technical subject matter, previously extracted in the process of construing the application, into technically meaningful keywords, synonyms, and concepts. By this is meant capturing all relevant technical details of the application into wording and jargon that is understandable to and generally used by experts or practitioners from the field(s) to which the application relates. This step is intricately linked to identifying the most pertinent technical classes in the relevant classification systems such as the CPC, IPC, or Japanese File Indexes and F-terms [10], [11], [12], [13]. As a result, the examiner will at this stage be in a position to classify the application by allocating a CPC and/or IPC classes.

In this way a two-dimensional matrix can be composed wherein the identified keywords and concepts are represented along one axis and the patent classes and any relevant non-patent literature databases (scientific, technical, standards, etc.) along the second axis. For most applications of any technical complexity, the number of cells defined by this matrix can be quite considerate. This immediately prompts the examiner to consider the question: “Which specific combination(s) of keywords and/or classes offers the best chances to find the most pertinent prior art quickly and perform a complete search?”

The answer to this question might depend on several considerations:

  • Would I rather expect to find relevant scientific publications (a clear hint towards emphasising non-patent databases) or mainly patent applications?
  • Is the technological activity in this field concentrated geographically (for instance, Asia)?
  • Who are the main players in this field? Are there just a limited number of very active applicants or, on the contrary, is the market dispersed?
  • What is the drafting and filing strategy of my applicant?
  • Given the nature of the subject matter, what are the most relevant databases and search tools? Is it more appropriate to perform a full text based search or rather figure based? Etc …

Taking all of these considerations into account might inspire the examiner to adopt a highly targeted and focussed search strategy (e.g. an initial query limited to a limited number of documents of country codes, applicants, classes and/or keywords) in an attempt to find the “magical bullet” (e.g. novelty destroying documents for the independent claims) quickly. This scenario might apply for an application in a high tech, innovative field with one or two key players, the invention being well-drafted using field-specific jargon and concepts, and one or two relevant technical classes to be allocated.

Alternatively, it might be more appropriate or necessary to adopt a broader, less focussed approach (“needle in the haystack”) necessitating filtering through and investigating large quantities of documents. The latter might arise in the case of low-tech inventions, with a high number of potential inventors or applicants, and several, possibly unrelated, markets in which the invention might be used or applied.

Moreover, the initially determined search strategy is not carved in stone: first prior art results will often lead the examiner to include new classes or incorporate additional keywords or synonyms. In other words, the constant evaluation of retrieved documentation is likely to influence the initially determined strategy. In this sense, the search process is inherently an iterative and adaptive process [14], [15].

6. Examination issues

An EPO examiner normally performs both the search and the subsequent substantive examination of a patent application. Moreover, the European search report comprises a search opinion. The latter contains the examiner’s opinion on whether the application and the corresponding invention satisfy the requirements of the EPC.

As a result, the examiner concentrates the search for prior art on the essential aspects of the disclosure firmly bearing in mind the potential influence and impact on the substantive examination process: e.g.

  • What are the key objections that need to be overcome to proceed to a grant or, alternatively, upon which a refusal is likely to be based?
  • What objections are peripheral or formal and can be easily remedied?
  • Can I identify patentable subject matter anywhere in the application (i.e. not only in the claims)? Can I formulate a corresponding proposal for the applicant?
  • Alternatively, can it be convincingly argued that further prosecution is likely to lead to a refusal of the application?

Clearly, the identification of the most pertinent prior art, in combination with a clear indication and argumentation of the likely direction of the subsequent examination procedure, allows the applicant to take better prosecution decisions and an informed decision concerning his prosecution strategy and increases the overall predictability and consistency of the search and examination process.

7. How “good” is my prior art?

In line with the above mentioned examination mindset, EPO examiners perform patentability searches [10] and essentially try to answer the question: “Is the claimed invention novel and inventive in the light of the available prior art?”

In case the examiner retrieves prior art that convincingly demonstrates the lack of novelty or inventive step of the independent claims, as well as of all fall-back embodiments (defined by the dependent claims or disclosed in the description or drawings), the search may be concluded.

In less clear-cut scenarios, the decision to pursue or to stop a search will eventually hinge on the examiner’s judgement call that the already retrieved prior art provides a solid and comprehensive answer to the patentability question for all disclosed subject matter. In this respect, the robustness of the experienced examiner’s decisions is based on his intimate knowledge of his technical field and his search expertise.

8. Balancing quality and efficiency

Delivering high quality and efficient services is the strategic cornerstone of the EPO’s operations and the EPO is consistently rated number one for patent quality among the world’s largest patent offices [16]. Key initiatives at an organisational level include engagement with our applicants and various other stakeholders and the adoption of numerous policies and practices to monitor and improve quality. This commitment has resulted in ISO 9001 certification of the EPO’s entire patent processes (including search, examination, opposition, limitation/revocation patent information and post-grant activities).

At the examiner’s level, this first of all translates into performing a comprehensive search which identifies the most pertinent prior art in a timely and efficient manner. This provides the strongest basis for legal certainty and validity of the subsequently granted patents.

In 2015, the EPO received almost 280000 filings, carried out about 238000 searches and granted about 68000 patents [17]. To manage this workload in a timely manner, examiners need to work highly effectively and efficiently, juggling a large portfolio of professional activities and pending applications.

In this respect, the examiners’ job is very comparable to that of many knowledge workers in service organisations. Broken down to the level of an individual search, an experienced examiner working in a technologically complex field can be expected to complete a full search in about 1,5 days. The latter represents a reference value that may vary with the complexity of the application and the level of experience and efficiency of the examiner.

Key HR and operational factors that enable and underpin this sustained high performance include:

  • recruitment of high quality candidates: PhDs, relevant professional experience, linguistic skills.
  • rigorous training programme, combined with a culture of career-long learning and knowledge transfer among peers [3].
  • Examiners specialize and work in narrow technical fields, promoting a culture of technical expertise, and in-depth knowledge of the applicants and their business environment, filing strategies and representatives.
  • Quality and output are key aspects in assessing performance, and form the basis for professional advancement.

9. Conclusions

Different from other types of prior art searches that are explorative or concern validity or freedom to operate analyses the EPO examiner will focus the search process on retrieving that prior art decisive for the patentability of an invention. His skills lie in the selection of relevant search tools and databases, the design of powerful queries and the interpretation of relevant prior art. His focus is on delivering high quality searches as a basis for granting strong patents and ensuring that, in full neutrality, a correct balance is struck between the disclosure and the scope of the granted monopoly.

As a technical and IP specialist this first of all requires a consistent and transparent application of the legal concepts and procedures defined by the EPC.

High quality has traditionally been the hallmark of the EPO. Upholding and improving this quality, in line with the EPO’s commitment to deliver its services efficiently, implies that the examiners’ role of legal administrator and arbiter is performed with a mindset of strong service orientation (esprit de service) towards its applicants, other stakeholders and society at large.


Over the course of several years this topic has been presented as lecture or workshop at the EPO’s Search Matters conference, where it was consistently received with great interest. The author is grateful to the many participants who, by their enthusiastic cooperation and questions, have contributed significantly to its contents and format, as reflected by the present article. The author further wishes to thank his EPO colleagues Thomas Bereuter (European Patent Academy) and Nigel Clarke (Patent Promotion) for their critical review of early drafts of the manuscript and helpful suggestions for improvements.


Any opinions expressed in this article are those of the author and not necessarily those of the European Patent Office.


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