Suppose they threw a party and no-one came? It wasn't quite like that when the supporters of open source software decide to lobby European lawmakers - but it was pretty close.

More than three hundred software developers and entrepreneurs opposed to granting patents on software programs attended a one-day conference at the European Parliament in Brussels, but they didn't invite the main target of their lobbying. Arlene McCarthy, a member of the legal affairs committee responsible for choosing the amendments to the proposed law to be tabled at next month's plenary session, said she wasn't invited to the conference.

The conference, which was hosted by the Green Party, had the aim of warning lawmakers of the dangers they see in passing a Europe-wide law on software patents. Patent protection, they argued, stifles innovation in software development among small companies and programmers by creating a legal minefield only the richest of corporations can navigate successfully.

The conference comes one month before the proposed directive on software patents is to be debated formally for the first time in the European Parliament. But the event, which included an elaborate lunch for delegates with cabaret entertainment on a roadside terrace in the heart of the European Parliament district in Brussels, may have caused more harm than good, said some Parliament officials.

"They were preaching to the converted. They should have been speaking to MEPs (members of the European Parliament) that favor software patents," said one..

Joint organizers of the conference from the European Free Alliance, a free software lobbying group, recognised their error in not inviting McCarthy until it was too late. A spokesman for the Alliance said McCarthy was also invited to submit a statement which would have been read out to delegates, but she declined the offer.

McCarthy's office said it did submit a statement but that it was never circulated at the conference. "It's not smart to snub the rapporteur on the lead committee responsible for guiding this debate. They won't have done themselves any favors by appearing to (disrespect) McCarthy," said one Parliament official who requested anonymity.

Speaking from her office while the conference lunch was in full swing in the street below, McCarthy accused the conference organizers of not wanting to hold an open debate.

She also said she will discard extreme amendments submitted by Green MEPs. "I won't accept amendments that exclude patentability per se," she said.

McCarthy, along with many MEPs from a wide range of political parties, believes a Europe-wide law on software patenting is required in order to harmonize law across the 15 member states of the Union.

She also believes that European software developers will be at a competitive disadvantage to their American counterparts without patent protection.

However, she agrees with opponents of the draft law that it would be wrong to have the level of protection granted to developers in the U.S., where mundane software devices can be registered for patent protection.

"I want to make it harder to get patents in Europe than at present," McCarthy said, adding that the Green party would be "mad" to vote against the amended version of the draft she favors.

But the message from the conference floor was clear. "We don't want patent protection, thank you very much," said Robert Dewar, president of Ada Core Technologies Inc., a small company based in New York with a division called ACT based in Paris, which sells programs and support mainly to defense companies such as Honeywell International Inc.

"The way to win is to keep innovating, not relying on software patents," he said. Dewar has acted as an expert witness for defendants in numerous patent infringement lawsuits. "As a small firm, you go unnoticed by the big software makers until you create something really special.

"Then you start to receive letters from patent lawyers representing big firms that either want to buy a license to your software at a cheap price, or they simply want to drive you out of business so they can pick up your idea for next to nothing in the bankruptcy court after you have been sunk by astronomical legal fees," Dewar said.

"A patent suit is the one thing that could sink us," he added.

"If Europe adopts this software patent law I'm going to have to redirect millions of dollars I planned to invest in European software firms into a fund to cover patent infringement suits," said Laura Creighton, co-founder of Swedish groupware developer AB Strakt and of a British publishing software company called Reportlab Inc.

Creighton became a millionaire during the Internet bubble and sold the bulk of her shares when prices were close to their peak in early 2000. She said she made her fortune mainly from E-Bay stock at a time when she herself was a software engineer. She now describes herself as a small-scale venture capitalist.

"I am the sort of person the European Union is looking for to help develop the European software market. Lawmakers should realize that this proposed law is putting me off," she said.

Creighton, Dewar and free software guru Richard Stallman, who also took part in the conference, all argue that the European lawmakers who aim to create a law that is more restrictive than the regime in the U.S. are misguided.

If the directive is passed, "there will be the same surge in patent applications in Europe that occurred in the U.S. in the late 1980s," Creighton said, pointing out that there are 30,000 patent applications already waiting to be legalized in Europe, including one for the ubiquitous progress bar used to show how a software download is progressing.

"They may want something short of what the U.S. permits in terms of patentabilty, but the reality is that European patent law will drift down the same path," Creighton said.

Although she largely agrees with him, Creighton doesn't share Stallman's evangelical approach to the debate.

"We do need laws to make sure software developers get paid for their work, but patent law is the wrong way to do it because patent law only benefits the big developers," she said.

McCarthy said the legal affairs committee will meet on Monday to try to narrow the wide range of amendments being proposed by MEPs from both sides of the debate. Another meeting may be necessary on May 20, ahead of a planned committee-level vote on May 21 and the Parliament-wide vote in early June, she said.

The proposal for a law was drafted by the European Commission, the executive body of the Union, early last year. It would allow patents only for software applications of a technical nature, and it would not permit patents on business methods.

The U.S. and Japan allow patents on a much wider range of software, and they both permit patents for business methods. Business methods include innovations such as one-click purchasing, for which the online retailer Amazon.com Inc. received a patent in the U.S. in 1999.

Amazon used the patent to get an injunction against use of a similar purchasing feature by a rival, Barnesandnoble.com, but an appeals court lifted that injunction last year.