Artificial intelligence continues to test the boundaries of UK patent law. Few cases illustrate this better than Emotional Perception AI Ltd v Comptroller-General of Patents, Designs and Trade Marks.
The decision addresses two key questions: whether artificial neural networks (ANNs) fall within the statutory exclusion for ‘computer programs’; and whether the UK’s longstanding approach to software patents remains fit for purpose.
The case arose from a 2019 patent application by Emotional Perception AI Ltd (EPAI). The invention concerned a system for recommending media content using an ANN trained to recognise similarities between files – such as music tracks – based on objective characteristics associated with human emotional perception.
The UK Intellectual Property Office (UKIPO) rejected the application under section 1(2) of the Patents Act 1977, which excludes certain subject matter from patentability, including computer programs ‘as such’. EPAI appealed, triggering a series of decisions that exposed growing uncertainty about how UK law should treat AI-based inventions.
In 2023, the High Court allowed the appeal, holding that a trained ANN did not fall within the computer program exclusion. The judge reasoned that the weights and biases generated through training were not traditional instructions written by a human programmer, but the product of the system’s learning process.
That interpretation proved short-lived. In 2024, the Court of Appeal overturned the decision and reinstated the refusal. The court adopted a broader definition of both ‘computer’ and ‘computer program’, concluding that the trained parameters of an ANN effectively operate as instructions causing a machine to process data in a particular way. On that basis, ANN-based inventions were to be assessed like any other computer-implemented invention under the established Aerotel framework.
The Supreme Court has now allowed EPAI’s appeal, delivering the most significant shift in UK patentability analysis in nearly two decades.
Most notably, the court held that the longstanding Aerotel framework should no longer be followed. The court considered that the Aerotel test – particularly its focus on identifying the ‘contribution’ made by the invention – risked conflating the question of whether subject matter qualifies as an invention with the separate requirements of novelty and inventive step.
Instead, the court endorsed the approach developed by the European Patent Office (EPO), particularly the reasoning of the Enlarged Board of Appeal in decision G1/19 (Pedestrian Simulation). The court emphasised that UK courts should generally follow established EPO jurisprudence unless convinced it is clearly wrong.
Under the framework now adopted, the analysis proceeds in three broad stages.
First, the ‘any hardware’ test asks whether the claimed method involves technical means. If the claim involves hardware – such as a computer or other technical device – it qualifies as an ‘invention’ under article 52(1) of the European Patent Convention. This sets a deliberately low threshold.
Second, examiners identify which features of the claim contribute to the invention’s technical character, filtering out non-technical elements such as purely abstract or cognitive aspects.
Finally, novelty and inventive step are assessed only by reference to those features that contribute to technical character.
While the court outlined this framework, it declined to provide detailed guidance on how the intermediate ‘technical character’ assessment should operate in practice, leaving further development to the UKIPO and lower courts. The Supreme Court also addressed directly whether ANNs fall within the exclusion for computer programs.
Rejecting the High Court’s distinction between hardware and software ANNs, the court concluded that an ANN is best understood as an abstract computational model capable of implementation in hardware or software. In either form, it effectively constitutes a set of instructions causing a machine to process data in a particular way.
On that basis, the court held that ANNs do fall within the concept of a computer program under the Patents Act 1977.
However, this does not mean AI-based inventions are automatically excluded from patentability. Applying the ‘any hardware’ approach, the court held that EPAI’s invention – which involved computer hardware implementing the ANN alongside databases, communications networks and user devices – was not a computer program ‘as such’. The presence of technical means meant the claim qualified as an invention and could proceed to be assessed for novelty and inventive step.
The judgment represents a realignment of UK patent law with EPO practice, removing a longstanding source of divergence between the UK and European patent regimes.
For businesses developing AI technologies, the ruling offers greater clarity but not necessarily an easier route to patent protection. While the ‘any hardware’ test lowers the bar for qualifying as an invention, the new intermediate stage places increased focus on whether the claimed features genuinely contribute to technical character.
In practical terms, applicants and advisers should consider:
- Reviewing pending UK patent applications, particularly those involving software, AI or data processing;
- Revisiting earlier refusals based on the Aerotel analysis, where the new framework may provide grounds for reconsideration;
- Aligning UK and European patent strategies, given the closer convergence between UK courts and the EPO; and
- Ensuring patent specifications clearly articulate the technical purpose and technical effects of AI-driven inventions.
As AI becomes increasingly central to commercial innovation, the Supreme Court decision provides long-awaited clarity. It also marks the beginning of a new phase in UK patent law, where the boundaries of ‘technical character’ in AI-related inventions will continue to evolve.
Winona Chan is legal counsel at Moneybox
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