UK Supreme Court Overhauls Patent Law Framework for AI and Neural Networks

Artificial intelligence continues to challenge the boundaries of UK patent law, with the recent Supreme Court decision in Emotional Perception AI Ltd v Comptroller-General of Patents, Designs and Trade Marks marking a significant turning point.

The case centered on two critical issues: whether artificial neural networks (ANNs) fall within the statutory exclusion for ‘computer programs’ under the Patents Act 1977, and whether the UK’s traditional approach to software patents remains appropriate in the evolving technological landscape.

Emotional Perception AI Ltd (EPAI) filed a patent application in 2019 for a system recommending media content using an ANN trained to identify similarities between files—such as music tracks—based on objective characteristics linked to 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, initiating a series of judicial decisions that highlighted increasing uncertainty over the treatment of AI inventions under UK law.

In 2023, the High Court allowed EPAI’s appeal, ruling that a trained ANN did not fall within the computer program exclusion. The court reasoned that the weights and biases generated through the ANN’s training process were not traditional human-written instructions but the product of machine learning.

However, this interpretation was overturned in 2024 by the Court of Appeal, which reinstated the refusal. The appellate court adopted a broader definition of ‘computer’ and ‘computer program’, concluding that the trained parameters of an ANN effectively function as instructions causing a machine to process data in a specific manner. Accordingly, ANN-based inventions were to be assessed under the established Aerotel framework for computer-implemented inventions.

The Supreme Court has now allowed EPAI’s appeal, delivering the most substantial shift in UK patentability analysis in nearly twenty years.

Most notably, the Supreme Court held that the Aerotel test should no longer be applied. The court criticized the Aerotel framework’s emphasis on identifying the invention’s ‘contribution’, noting that it risked conflating the question of patentable subject matter with the separate requirements of novelty and inventive step.

Instead, the court endorsed the European Patent Office’s (EPO) approach, particularly the reasoning in the Enlarged Board of Appeal decision G1/19 (Pedestrian Simulation). The Supreme Court emphasized that UK courts should generally follow established EPO jurisprudence unless it is clearly erroneous.

The newly endorsed framework involves a three-step analysis. First, the ‘any hardware’ test determines whether the claimed method involves technical means, such as a computer or other technical device, thereby qualifying as an ‘invention’ under article 52(1) of the European Patent Convention. This sets a deliberately low threshold.

Second, examiners identify which claim features contribute to the invention’s technical character, filtering out non-technical elements like abstract or purely cognitive aspects.

Finally, novelty and inventive step are assessed solely by reference to those features that contribute to technical character.

While the Supreme Court outlined this framework, it refrained from providing detailed guidance on the intermediate ‘technical character’ assessment, leaving its further development to the UKIPO and lower courts.

The court also directly addressed whether ANNs fall within the computer program exclusion. Rejecting the High Court’s distinction between hardware and software implementations of ANNs, the Supreme Court concluded that an ANN is best understood as an abstract computational model capable of implementation in either hardware or software. In both forms, it effectively constitutes a set of instructions causing a machine to process data in a specific way.

Accordingly, 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’ test, the court found 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.