The European Union's proposed software patent rules are a major threat to interoperability unless specific exemptions are made to upcoming legislation, conference-goers were told today in Brussels.

The two-day event hopes to build support against changes in the patent law before the European Parliament debates the issue again in the new year.

Simon Phipps, Sun's chief technology evangelist, said that the software patent directive should maintain existing exemptions that allow reverse engineering in the interests of interoperability. If this exemption is not preserved, he said: "All is lost."

According to Phipps, Sun believed that "interoperability was key to the freedom of consumers" and protecting it required looking at the effects of the legislation on interoperability.

Jean-Francois Abramatic, vice president for research and development at software developer Ilog and former chairman of World Wide Web Consortium (W3C), backed Phipps' view. Abramatic said he encouraged the European Parliament to re-examine the legislation to ensure that patent protection would not undermine efforts to create effective industry standards. "Interoperability of any kind of software is a feature which benefits the whole community at large so any action from legislators to encourage interoperability is welcome," he said.

Drawing on his own experience at the W3C, Abramatic said that the organisation drew up very strict rules on declaration of patent interests to ensure that efforts to create common standards were not jeopardised by participants "patent farming" - that is, only declaring they have intellectual property rights once a standard has been developed.

The conference also heard from Koen Martens of the Sender Policy Framework (SPF), an organisation that is developing an email identification standard to combat spam, phishing and other forms of Internet abuse.

Martens explained that his group lost a year's work after some of the program's major participants, including the Apache Software Foundation, the Debian Project and several open source software developers, left because Microsoft held patent rights on some of the technologies used to identify senders. Members feared that Microsoft would exploit its patent rights and legally challenge technologies derived from SPF's work. "We debated a year on licences. We could have had a proper standard by now but we wasted a year," Martens said.

The two-day conference is being hosted by the Foundation for a Free Information Infrastructure, the Green/European Free Alliance group in the European Parliament and the Open Society Institute, among others.

Under the EU's co-decision procedure, the European Parliament gives its opinion early next year on a compromise reached by member states in the Council of Ministers in May. The open source software community heavily criticised that draft. Florian Muller, campaigns manager for Nosoftwarepatents.org, a group backed by Red Hat, MySQL and German Internet firm 1&1 Internet, called the Council's text the "most pro-software patent proposal in Europe".

However, the industry association of leading IT and telecom companies, EICTA, supports the Council's version and last month urged the European Parliament to back the proposal, warning that Europe would become a "plagiarists' paradise" without the measures.