The subject has been thrown into sharp relief by two significant cases brought before UK courts: Macrossan and Aerotel v Telco. While the former focused on a decision by the UK Patent Office (now the UK Intellectual Property Office, or UK-IPO) to deny a patent for software guru Neal Macrossan's document sorting system, the latter concerned a challenge to Aerotel's tool for networking computer terminals. In November 2006, Telco's challenge against Aerotel was dismissed by the UK Court of Appeal. Yet on the same day, the court upheld the ruling on Macrossan's patent application.

Crucially, Aerotel's tool was deemed to have a patentable effect on hardware, while Macrossan's system was classed as a business method. Macrossan took his appeal to the UK House of Lords, but in February 2007, his bid to revisit the case there was turned down. In both cases, UK courts followed article 52 – sections (2) and (3) – of the European Patent Convention (EPC), which recommends that computer programs with technical effects in reality are patentable, while computer programs 'as such' are not. Brimelow's request to her own EBoA illustrates the pivotal role that the phrase 'as such' has played in the interpretation of the law: many IP insiders have viewed it as equivocal.

While clearly prompted by the above cases, Brimelow's referral marshals a recent history of 'divergent decisions' on the finer points of article 52. One example she cites is a February 2006 decision to patent a Microsoft-developed clipboard tool for transferring data. In this case, the tool's chosen category was 'computer-implemented method', and it was found to have technical character. The major concerns that emerge from her argument are whether the language of a claim, by itself, can affect a program's chances of patentability; and whether the effects of a program must be visible in reality in order to make it patentable. This is reflected in her four questions to the EBoA:

• Can a computer program only be excluded as a computer program as such if it is explicitly claimed as a computer program? (This question addresses the nature of claim-construction – could a program avoid exclusion by claiming to be something more?)
• Can a claim in the area of computer programs avoid exclusion … merely by explicitly mentioning the use of a computer or a computer-readable data storage medium?
• Must a claimed feature cause a technical effect on a physical entity in the real world in order to contribute to the technical character of the claim?
• Does the activity of programming a computer necessarily involve technical considerations?

'As the EPC was drafted,' Brimelow explains, 'the feeling was that it was better not to define the exclusion precisely in law, but rather that the matter should be left in the hands of the EPO and the national courts. This flexibility is important as technology develops and new technologies emerge. Nevertheless,' she adds, 'diverging decisions of the boards of appeal have indeed created uncertainty, and answers to the questions arising from these decisions are necessary.'

Reaction to the referral has so far been mixed. Mark Kenrick, Partner at leading IP law firm Marks & Clerk, said that while 'further clarification of the law will of course be welcome in the long term,' the EPO had already created 'a workable and understandable approach.'