A New Era for AI Patents in the UK: Supreme Court Aligns with the EPO

The UK Supreme Court has handed down its long-awaited judgment in Emotional Perception AI Limited (EPAI) vs Comptroller General of Patents, a decision which serves to significantly change the way in which the patentability of AI (and computer-implemented inventions more widely) is assessed in the UK.

The Supreme Court’s judgment finds that the existing approach of the UK courts (the so-called Aerotel approach) should be abandoned and replaced with the approach adopted by the European Patent Office (EPO).  This harmonisation with the EPO’s approach is a significant change in UK patent law, provides greater legal certainty, and is likely to herald a more favourable environment for innovators seeking patent protection in the UK for computer-implemented inventions.

Background

Recent years have seen an enormous increase in the use and development of AI.  As well as news headlines, this increase has also been reflected in large increases in the number of patent applications filed for inventions directed to, or utilising, AI.

However, obtaining patent protection for AI-related inventions in the UK and Europe more widely is often not straightforward.  This is because both the UK Intellectual Property Office (UKIPO) and the EPO typically treat the training and implementation of AI as being mathematical methods implemented by computer programs.  This is significant because computer programs and mathematical methods “as such” are excluded from patentability by statute.  As a result, many of the headline-grabbing AI innovations which are the topic of the news do not always relate to patentable inventions in the UK and  Europe.

Whilst both the UK and the EPO apply exclusions to patentability for computer programs, there have to date been significant differences in the way that these exclusions are applied in the UK and at the EPO.  In practice, this has often made the EPO a more favourable forum for seeking patent protection for computer-implemented inventions and AI than the UK.

The Aerotel approach applied in the UK (following the judgment in Aerotel Ltd v Telco Holdings Ltd [2007] RPC 7) often serves to exclude computer-implemented inventions from patentability from the outset and without detailed consideration of any differences between the invention and the prior art.  The UKIPO will often refuse to conduct any prior‑art search (whereas the EPO generally will), which is a frequent source of frustration for applicants.

The Emotional Perception Application

The judgment concerns a UK patent application first filed by Emotional Perception AI Limited (EPAI) in 2019.  The application relates to providing semantically similar file recommendations.  The most prominent example of this is identifying a semantically similar music file to a target music file.

The semantic similarity between two files is determined using an artificial neural network (ANN).  The ANN is specifically trained to output a property vector representing semantic properties (such as “happy,” “sad,” or “relaxing”) of a file, based on an input representing measurable properties of the file (e.g., tone, timbre, speed, loudness, etc. in the case of a music file).  Once property vectors have been generated for multiple files, distances between those vectors can be calculated to provide a quantitative measure of semantic similarity between the files.

History of Previous Decisions

In 2022, the UKIPO refused EPAI’s patent application for relating to subject matter which is excluded from patentability.  In particular, the UKIPO considered the claimed ANN to be a computer program “as such” and thus excluded from patentability in the UK.

This refusal was appealed to the High Court which issued a groundbreaking judgment in 2023, deciding that a trained ANN was not a computer program at all.  The High Court drew a distinction compared with a traditional computer program, since the weights of a trained ANN had been learned through training rather than input by a human programmer.  At the time, this decision seemed to open up patentability to a much wider class of AI related inventions and establish the UK as a highly attractive forum for AI innovators.

However, in 2024 the Court of Appeal overturned the High Court decision, holding that a trained ANN is a computer program after all, and that the topology and weights of the ANN serve as instructions to a computer as to how to implement the ANN.  In reaching this conclusion, the Court of Appeal also provided a broad definition of a computer that some feared would serve to encompass a much broader class of inventions into the computer program exclusion and thereby render the UK a highly restrictive forum for seeking patent protection for computer-implemented inventions.

The Supreme Court Judgment

In their judgment, the Supreme Court decided on three issues, which are summarised below.

Issue 1: Should Aerotel no longer be followed?

The Aerotel approach to assessing exclusions to patentability has been followed in the UK for nearly two decades.  Crucially, the Aerotel approach can be used to decide that patent claims are excluded from patentability for being directed to a computer program, even when the claim specifies that the program is executed on hardware.

The judgment finds that the Aerotel approach is incompatible with a decision of the Enlarged Board of Appeal of the EPO (G1/19) which confirms the EPO’s “any-hardware” approach.  Under the “any-hardware” approach, if a claim specifies the use of hardware (e.g., a general-purpose computer) to execute a program, then it no longer falls within the computer program exclusion.  In practice, therefore, the computer program exclusion can be very easily avoided by specifying the use of some form of hardware in the claim.

The judgment finds that (at least in part due to this incompatibility) the Aerotel approach should no longer be followed in the UK and should be replaced by the G1/19 “any-hardware” approach. This shift to the “any-hardware” approach in the UK serves to severely restrict the use of the computer program exclusion to patentability in the UK, and significantly harmonises practice with the EPO.

Issue 2: Is an ANN (or does it contain) a “program for a computer”?

On issue 2, the Supreme Court agreed with the Court of Appeal that an ANN is a program for a computer, since the weights and topology of an ANN serve as instructions to a computer for executing the ANN.  No special significance is afforded to instructions created by a computer (e.g., through machine-learning) and those created by a human.  The judgment therefore confirms that AI and machine learning techniques should be seen as computer programs like any other.

Notably, the Supreme Court did however, refuse to endorse the wide definition of a computer which was advanced by the Court of Appeal, thereby avoiding bringing a much broader class of inventions into the computer program exclusion.

Issue 3: Is the entire subject matter of the claims excluded?

Whilst it was held that an ANN is a program for a computer, the claims of EPAI’s application specify the use of computer hardware to carry out the invention.  The Supreme Court’s new adoption of the EPO’s “any-hardware” approach (as decided under Issue 1) therefore means that the claims of EPAI’s application are found not to be directed to a computer program “as such” and thus are not excluded from patentability.  The judgment therefore finds that the UKIPO and the Court of Appeal were wrong to decide that EPAI’s application should be refused for being excluded from patentability as a computer program.

Whilst the computer program exclusion no longer applies to EPAI’s claims, the EPO’s G1/19 approach requires the undertaking of a so-called “intermediate step” in which it is established whether a claim feature contributes to the technical character of the invention (and can therefore contribute to an inventive step).  It is this “intermediate step” which is the most significant hurdle to overcome for computer-implemented inventions under the EPO’s approach and can lead to a finding of a lack of inventive step.

Whilst the judgment confirms that the “intermediate step” should be applied to the claims of EPAI’s application to decide whether or not they are inventive, the Supreme Court refrains from doing so.  Instead the appeal has been allowed, (on the grounds that EPAI’s application is not excluded from patentability) and the application has been referred back to the Hearing Officer of the UKIPO to decide whether or not EPAI’s application is inventive over the prior art using the “intermediate step” approach.

The Consequences

With the Aerotel approach now abandoned in favour of the EPO’s G1/19 framework, avoiding the computer program exclusion in the UK should become significantly easier.  The judgment also ushers in much closer alignment between outcomes at the UKIPO and the EPO, a development likely to be welcomed by both innovators and patent practitioners.

However, while Aerotel set a high bar for overcoming the computer program exclusion, this judgment shifts the main battleground to the question of inventive step.  The Supreme Court confirms the need for an “intermediate step,” requiring that claim features contribute to the technical character of the invention in order to support an inventive step.

Crucially, though, the Court deliberately stops short of creating binding precedent on how this “intermediate step” should be applied in practice or what is required for a feature to contribute to the technical character of a claim.

There therefore remains ample scope for the UKIPO and future decisions of the UK courts to develop how the patentability of computer‑implemented inventions is assessed under this new framework.

This article was prepared by Partner & Patent Attorney Nick King and Senior Patent Attorney Emily Thao.