Linux users in the UK could face a greater threat from Microsoft than previously thought, but experts agree that British open-source users are in far less danger than US users from Microsoft's claim that open-source software infringes its patents.
Microsoft has claimed that Linux and other open-source software infringes 235 of its patents. Although the company has refused to say which patents are involved, the risk must be lower in the UK than the US, because the company has far fewer patents in the UK, argued Andrew Katz, a solicitor at Moorcrofts, last week.
However, Microsoft does have more patents affecting the UK than the 51 UK patent applications Katz quoted, because Redmond also has a few hundred European patents which might have force here, depending on the decisions of UK courts, said David Pearce, an associate at Nottingham-based patent attorneys Eric Potter Clarkson, on the IPKat blog.
"Even if 400 apply in the UK, this is a vastly smaller number than the amount that apply in the US," said Katz. "It demonstrates that the UK regime is vastly different to the US regime, which is the main point that needs to be drawn out."
According to Katz, the European Patent Office has granted 431 patents to Microsoft, out of 4,341 applications. Over 7,000 patents have been granted to Microsoft in the US.
European patents are more attractive than UK patents, explained Pearce. "For obvious reasons, and not just those relating to cost, most big companies nowadays much prefer to prosecute their patent applications before the European Patent Office rather than the UK Intellectual Property Office."
"I'd never suggest that anyone should base risk management purely on the number of patents granted," warned Katz.
However, of Microsoft's 431 European patents, many will be irrelevant to the Linux case, as they deal with hardware issues, such as mice.
"In a very brief and non-scientific scan of the 51 applications made through the UK patent office, the proportion of patents which were hardware-related seemed significantly higher than a quick random sample of [Microsoft's] US patents," said Katz.
Europe's stance against software patents is not as firm as Katz said, according to Pearce. "Europe does indeed 'do' software patents, and has done for many years," he said.
Since 1999, patents have been issued for computer program products, according to complex criteria. "[It] depends on something to do with a 'technical effect', that is, an effect beyond that of a mere computer program," Pearce explained. "This is easier to understand when computers are used to control industrial processes, but less so when applied to general-purpose computer applications."
These criteria are just "loopholes", by which patent agents try to get round a European statutory exclusion for the patentability of computer software, said Pearce. "The European Patent Convention and the Patents Act make it clear that computer software 'as such' is not patentable. This obviously generates a lot of debate as to what 'as such' means."
If its Linux patents are legal in the UK, Microsoft would have to sue for "indirect infringement" — a supplier of computer programs providing the means to put Microsoft's invention into effect — rather than "direct infringement" — a supplier providing infringing computer programs.
"The difference is one of level and burden of proof, and effectively makes it harder to enforce the relevant patents," said Pearce. "The patents would not, however, necessarily be invalid as a whole, just in part. This would not prevent Microsoft from suing anyone — just make it a bit harder for them to win."
So both are agreed that Microsoft is much less likely to bring any patent-infringement cases against open-source users in the UK. The UK Intellectual Property Office doesn't grant computer program patents any more, since two recent applications (Aerotel and Macrossan) were rejected.
However, the status of patents already in existence is not clear without more case law, said Pearce.