A new plan by the Open Source Development Labs (OSDL) designed to protect open source projects from patent lawsuits has already attracted criticism from the US and Europe, with critics arguing the project will be effectively useless against the patent threat.

Software patents are useful for large IT companies such as IBM, Microsoft and Hewlett-Packard, which have large patent arsenals that can be used to lock smaller rivals out of competition, according to patent experts. Such arsenals are also routinely used as protection against other large IT companies, with big companies routinely entering into cross-licensing agreements to settle disputes.

Smaller, independent software developers and open-source projects are considered particularly vulnerable to threats of patent infringement. Large companies have also begun advocating minor reforms to the US software patent system of late, as they have become more frequently targeted by patent-infringement lawsuits such as the Microsoft-Eolas case.

The OSDL's Patent Commons initiative, introduced this week at the LinuxWorld trade show, aims to collect the software licenses and patents pledged to the open source community into a central repository. The aim is to provide easier access to developers, and to encourage more patent holders to pledge their intellectual property to the cause.

The OSDL hopes Patent Commons will help encourage more companies to pledge their IP to the open source community, following the lead of IBM, Nokia, Novell, Red Hat and Sun.

There's just one problem, however, said open source activist Bruce Perens in a Thursday talk at LinuxWorld - the plan is next to useless. For one thing, companies such as IBM and Sun donating the use of their patents to open-source projects doesn't change much, since those companies are "friends" of open source rather than "enemies", and would be unlikely to sue open-source projects anyway, Perens said.

A central aim of the patent pool is to give the open source community a body of patents to draw on for cross-licensing arrangements like those commonly reached between large IT companies. But this is unlikely to work, said Perens, because of the cross-licensing arrangements already in place.

In other words, potential enemies such as Microsoft already have the right to use patents donated to the open-source community by IBM, Nokia, Sun and others, Perens said. "The pool unfortunately turns out to be spitting in the wind," he told attendees. Instead, the software industry should push for legislative changes, he said.

In Europe the plan got equally short shrift from Florian Mueller, one of the main campaigners against a recent attempt to make software patents easier to enforce in the European Union. The Patent Commons could only be effective if it were able to provide the open source community with a real patent arsenal, he said.

"The software patent game is like the Cold War: the only thing that protects you is the concept of mutually assured destruction," Mueller said.

He criticised pledges by IBM, Sun and others earlier this year to allow open-source projects to use their patents without fear of legal action, but said the OSDL project could prove more valuable. "The patent pledges added absolutely nothing to the retaliatory potential of open source," he said.

In January, IBM donated 500 patents to the open-source community, but at the same time was one of the main backers of the proposed Directive on the Patentability of Computer Implemented Inventions, which critics said would have made software patents easily enforceable in the EU.

Last month, the European Parliament voted overwhelmingly to scrap the directive, leaving European software patents in a grey area. The European Patent Office and national patent offices have already granted tens of thousands of software patents, but courts in some member states have declared many of them invalid, making their enforcement across the region impractical.