Concern has grown over the past year that Linux could be under legal threat from claims it infringes certain software patents.

No court cases have been filed, but the issue is serious enough that several companies have pledged not to use their patent portfolios against the open source operating system.

An industry consortium devoted to Linux, Open Source Development Lab (OSDL) has decided to coordinate this process. OSDL launched a Web site last week to help developers check which patents have been pledged. Patent Commons contains more than 500 patents so far, but that may not be enough to significantly affect the problem.

Some activists have claimed that the whole concept of patent pledges is misguided. ZDNet Australia sister site ZDNet UK spoke with OSDL Chief Executive Stuart Cohen to understand the wider aims of the project.

Q: Why have you launched Patent Commons today?
Cohen: Over the past year, several companies have made patent pledges, showing their commitment to the open source community in different ways. In August we announced we would create Patent Commons, and this is the public launch naming our partners.

What does Patent Commons offer?
It gives IT professionals and vendors a single place to go to see which patents have been pledged; it's a leaping-off point from where they can drive added value.

But presumably developers still can't be sure that they won't infringe patents that haven't been pledged?
Yes, there are so many patents out there, so people may still infringe. This is the first step forward.

Which companies are supporting the Patent Commons?
We're being supported by Intel, IBM, Sun, Computer Associates, Nokia, Ericsson and Red Hat -- they've all pledged their support publicly.

We would like to see Microsoft make some of its patents available.

Why aren't there more already?
It's a question of education and awareness.

Are there any particular companies you'd like to see join?
We would like to see Microsoft make some of its patents available. Microsoft is still evaluating where open source and open standards fit into its strategy, and they've been hearing from a number of customers who want interoperability between Windows on the server and Linux on the server.

Isn't Microsoft the big enemy? If anyone's going to bring legal action against Linux for alleged patent violation...
A lot of people who have a lot of patents have looked at this issue, and nothing's come of it. It's now a question of how we can make developers more productive.

You aren't worried that Linux could be hit by an intellectual property infringement case?
What was once a fear has now gone.

The Open Source Risk Management group claimed last year that Linux potentially violated over 200 patents. Are those patents all included in the Commons?
We can't say that. Those patents were never actually named, so no one knows which ones they are.

You're still confident that Linux is protected?
There's always been a suspicion that some of those patents were held by Microsoft. So, as Microsoft has not pledged any patents to the open source community, this could be an issue. But, our customer advisers speak to people, including major customers who run both Windows and Linux, and they say it's not an issue.

Which other companies would you like to join the Commons?
There are several, including HP, Oracle, SAP, NEC. But now that the Commons is out there, giving developers a single place to check patents that have been pledged...who cannot support that?

What's the incentive to pledge patents in this way?
Pledging patents creates the opportunity for more software, hardware, services to be developed around Linux.

So what's the difference between Patent Commons and the Open Innovation Network?
The two initiatives are complementary but different. The Open Innovation Network is acquiring patents and offering them on a licence-free basis. Although we may acquire a few patents, with Patent Commons the companies involved continue to own their patents.

We both have the intention of accelerating Linux -- while they are Linux-only, we are supporting Linux and open source. It's a very compatible partnership.

Is there any crossover?
No, but they could pledge their patents to Patent Commons.

Would you like them to do that?
We'd probably expect them to, but we don't know it as a fact.

Graeme Wearden reported for ZDNet UK.