Emotional Perception AI Limited (EPL)'s invention was an improved system for providing media file recommendations (such as music), based on human emotions. The invention used labelled training data – for example semantic classifiers, such as "happy" or "sad" to associate the semantic nature of music tracks with their physical properties. The Court of Appeal, overturning the first instance decision, held that artificial neural networks (ANNs) (as used in EPL’s invention) are computers like any other. They can therefore fall within the "computer program" exclusion from patentable subject matter unless the invention makes a “technical contribution”, which EPL had failed to show. EPL appealed to the Supreme Court.