Data – How Much Is Enough?

Marks & Clerk


Marks & Clerk is one of the UK’s foremost firms of Patent and Trade Mark Attorneys. Our attorneys and solicitors are wired directly into the UK’s leading business and innovation economies. Alongside this we have offices in 9 international locations covering the EU, Canada and Asia, meaning we offer clients the best possible service locally, nationally and internationally.
At the point of preparing a patent application, innovators will often ask questions along the lines of "How much experimental data do we need?"
UK Intellectual Property
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At the point of preparing a patent application, innovators will often ask questions along the lines of "How much experimental data do we need?", "Do we need to include all of our experiments?", and "Can we keep the patent as vague as possible as we would prefer to keep the true invention secret?". The answers to these questions, perhaps unsurprisingly, depend on the facts and the type of technology. Seeking the guidance of a patent attorney on these matters will help to ensure your patent application doesn't fall at the first hurdle. In this article, we provide a brief 'cheat sheet' for innovators in the life sciences space, which may provide some useful guidance on data requirements for patentability, and even help to spot where an invention has been made.

The Legal Background

The first point for innovators to keep in mind is that disclosure of the invention is inescapable, to the extent certain legal requirements for obtaining a patent are satisfied. Under European practice, it is unlikely patent protection will be obtained by holding back crucial and essential information relating to what the invention is, and even if a patent is obtained, vague descriptions of the invention can leave a patent vulnerable to attack by third parties. In other words, you can't have your cake (patent) and eat it (hide the invention through ingestion or otherwise).

Patent protection is effectively a trade between the innovator and the state. In return for a monopoly period relating to an invention, it is a requirement that the invention be disclosed to the public in a 'sufficient' matter. Sufficiency of disclosure is enshrined in Article 83 EPC, and is therefore an express requirement for obtaining a European patent. For an invention to be 'sufficiently' disclosed, the application must contain adequate information to allow the person skilled in the art, using common general knowledge, to perform the invention over the whole area claimed without undue burden and without needing inventive skill. Under European practice, an objection of lack of sufficient disclosure presupposes that there are "serious doubts, substantiated by verifiable facts", that the skilled person would be able to perform the invention. The burden of proof in such an objection generally lies with the party raising the objection (e.g. an Examiner or Opponent). As such, provided the skilled person could carry out the claimed invention based on the disclosure – or at least if the party raising the objection cannot convincingly demonstrate these serious doubts or verifiable facts – the sufficiency requirement should be satisfied. Sufficiency may therefore be considered to be a mechanism for the prevention of speculative patent applications progressing to grant.

A second point for innovators to consider is what does their invention achieve over what has gone before (the so-called 'prior art'), and how much data is required to demonstrate the achievement (or technical effect) is indeed achieved across the whole area claimed? This second point relates to a further requirement for patentability, namely inventive step which is enshrined in Article 56 EPC. The problem-solution approach, favoured by the EPO for evaluating inventive step, requires the analysis of a technical effect achieved by one or more differences or distinguishing claim features over the closest prior art. To assist with evaluating whether a purported technical effect is achieved across the entire scope of a claim, European case law developed a criterion commonly referred to as 'plausibility'.

Plausibility relates specifically to whether the problem purported to be solved by the invention is indeed solved across the entire scope of the claim. As such, and in contrast to sufficiency, plausibility is not a requirement of patentability per se under the EPC, but is rather a criterion which has evolved through European Case Law against which technical effects may be evaluated for the purposes of inventive step. Exemplary data may be provided in the patent application as filed to support a technical effect, and that data must be adequate enough to make an invention 'plausible' across the entire scope of the claim. Notably, in a recent decision (G2/21), the Enlarged Board of Appeal indicated the use of post-filed data to buttress data in the application as originally filed is permissible, provided said data supports the technical effect as disclosed in the application as originally filed. As discussed in our recent articles (here and here), in view of this recent decision, the EPO may be moving away from using 'plausibility' as an explicit criterion for evaluating inventive step, but it seems highly likely the underpinning rationale behind plausibility being developed as a concept in the first place will remain. Whilst the case law continues to develop, and in the absence of alternative terminology, it is helpful to continue to refer to 'plausibility' in the meantime.

With a view to considering the amount of data that is required in a patent application, another way of thinking of plausibility is whether the claim is actually speculative, and it is highly doubtful that the invention would work across the scope of the claim. This issue generally arises because it is desirable to describe an invention in its most general form, so as to provide a broad scope of protection for the innovator, thereby (hopefully) mitigating the risk of third parties circumventing the patent by making obvious and minor modifications to the technology. At the point of preparing a patent application, a patent attorney will consider the key elements of your invention, and use this as the basis for preparing claims. The terminology used in the claims may be 'generalised' terminology relative to the exemplary data provided.

As such, the concept of plausibility generally comes into play where the scope of a claim is broader than comparatively narrower examples. The greater the breadth of the claim compared to the disclosure provided in the examples, the more likely it is 'plausibility' objections will be raised by the EPO. For instance, if you discover new super-durable paint composition which requires gold flakes and this is your only example in a patent application, your chances of obtaining a patent may diminish as your claim broadens from gold flakes, to noble metals, to transition metals, to metals in general. Conversely, the risk of encountering objections is reduced if you also have examples also demonstrating silver, platinum, iron and magnesium all provide the same increase in durability. With this in mind, for the innovator, it is worth considering aspects of your invention which may be substituted for alternatives, and carrying out validation experiments in relation to those alternatives.

Technology & Data

As mentioned above, the amount of data required will ultimately depend on the facts, and where the invention lies. Engaging with a patent attorney at an early stage can help innovators identify inventions, and facilitate an understanding of additional data which may be required to make a robust patent application. However, as a first port of call, the technology itself can sometimes give an indication of the amount and type of data that will be required. The following discussion provides innovators with some pointers as to when 'enough' data has been generated to proceed with a patent application.


When it comes to devices, a single example of a working device together with a detailed description of how that device works may be generally adequate to meet the requirement for sufficient disclosure. This is because claims to devices generally focus on physical components of a device, and how those components are configured to work together to achieve a desired technical effect that underpins the invention. Provided the skilled person could go away and make that device based on what is disclosed in the patent application and use it, then the requirements for sufficiency will generally be met. For device claims, the concept of plausibility arises relatively rarely, compared to claims to therapeutics for instance (see below). This is because it can be more readily understood by a person skilled in the art whether a generalised form of a physical component would mean the purported technical effect underpinning the invention would be achieved. In other words, it can be more readily understood whether a generalised feature would still solve the problem purportedly solved by the invention. However, the issue of plausibility may arise where the novel and inventive feature of a device is a specific feature of a component comprised in the device. As such, a claim may require a component made of a certain material (e.g. a new coating applied to the exterior of the device which reduces adherence to tissues in vivo), or a component having a specific geometry (e.g. a cannula having certain dimensions that make it easier to insert into vasculature). In such instances, it is good practice to include exemplary data demonstrating that the technical benefits of the invention are also achieved for alternatives which may be encompassed by a claim covering the invention. These additional experiments will not only provide support for a broader claim scope, but in certain circumstances may be a source of comparative data. Comparative data can help to demonstrate that your 'preferred' embodiment provides technical benefits compared to other (relatively poorly performing) alternatives, which in certain circumstances can be of vital importance in successfully demonstrating that the claims show an inventive step.

Compounds & Substances

For inventions defined by a claim relating to a single novel and inventive compound per se, it is generally required that at least one method of synthesising or obtaining that compound is disclosed in the patent application, together with characterising data (e.g. 1H NMR, etc). This is so that the skilled person can carry out the invention by actually preparing the compound. On the other hand, where the claim relates to a wide array of compounds covered by a single claim (e.g. using a Markush formula) experimental data should also be provided showing that the exemplary inventive compounds covered by the broad claim have indeed been successfully prepared. Of course, where a claim covers a vast number of compounds, it must be plausible that the skilled person would be able to prepare compounds comprised in the claim scope without undue burden or experimentation, using their common general knowledge.

However, it is rare that novel compounds or substances are prepared without having a particular application, and indeed it is a requirement for patentability that an invention has industrial applicability. For this reason, for inventions relating to compounds and compositions, it is also important to consider data relating to use of those compounds.

For inventions relating to novel and inventive compounds, and also their use, then a single example relating to the use may be adequate for the purposes of sufficiency. For example, a new class of compounds could have been developed which provide compositions that are effective anti-fog formulations on swimming goggles. However, where the use is not simply a demonstration that a substance or composition 'works', but rather that it provides an improvement or benefit, then comparative data will likely be required. For instance, if two compounds are known from the prior art for a particular use, and the invention lies in a 'surprising' discovery that both compounds in combination provide unexpectedly improved performance in relation to that use, then providing data may be less important for the purposes of meeting sufficiency requirements, but will likely be essential for meeting the requirements of inventive step. This is because comparative data would be required to demonstrate the purported enhanced improvement of the combination, and to show that such enhancement could not have been predicted based on the performance of the individual compounds separately. In such instances, it may even be necessary to demonstrate that the claimed combination is a synergistic combination, relative to the performance of individual compounds alone.


Similar considerations for claims directed to therapeutic inventions apply to those outlined above in relation to compounds and substances. However, for therapeutics, there is the additional complication of demonstrating that the therapy is indeed medically effective. Under European practice, it is possible to obtain patent protection for compounds or substances for use in a method of treatment, even if those compounds or substances were known in the prior art, subject to the proviso their use in that method of treatment was previously unknown. To plausibly demonstrate that the medical condition to be treated is indeed treated, pre-clinical data is generally adequate. This is because it is generally understood that pre-clinical data provides indicative data that the therapy will plausibly also be effective in a patient. Nevertheless, anecdotal or early stage clinical data can sometimes be useful supporting data, especially where the pre-clinical data focuses on manipulations to the underlying molecular biology that is associated with the disease.

Where to begin and where to stop

Ultimately, the question of the amount of data that is required is highly subjective, and requires an analysis of the prior art, the nature and scope of the invention, and what the inventive contribution of the invention is. Having this information to hand can help to guide an innovator in understanding the level of data that will be required, and when is the appropriate time to approach a patent attorney for further guidance. Whilst the amount of data required for a patent is generally less than an academic publication for instance, the type of data may differ depending on what the invention is determined to be. There is probably no 'ideal' time for filing a patent application – a trade-off must be made between filing the 'perfect' patent application with data that exhaustively covers all possible embodiments falling within the scope of an ideal broad claim, and the need to secure legal certainty by obtaining a filing date. Delaying filing a patent application indefinitely may lead to third parties independently devising the invention, possibly scuppering your own chances of securing patent protection. For early stage companies, the benefits (e.g. attracting inward investment) of getting an application filed sooner rather than later is likely to outweigh the risks of disclosing preliminary data in the application and obtaining a narrower claim scope. Of course, seeking advice from a patent attorney will be invaluable in deciding when is the 'right' time rather than the 'perfect' time to file an application.

The content of this article is intended to provide a general guide to the subject matter. Specialist advice should be sought about your specific circumstances.

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