Microsoft is preparing an all-out war against Linux using patents, Lawrence Lessig claimed at the Open Source Business Conference in San Francisco.

Lessig is a law professor at Stanford University, a board member for the Electronic Frontier Foundation and considered a visionary in the field of copyright legislation.

"We hear a huge sucking sound out of Redmond," he said.

"A sucking sound of them hiring as many patent lawyers as we can produce."

Microsoft last year made $8.1b in profits. According to Lessig, past monopolies have shown us that the company will spend whatever it has to, to protect its current position.

Given Microsoft's size, he said, the company will use funds "far beyond what any of us is capable to imagine."

Microsoft chairman Bill Gates back in 1991 already recognized the power of patents when Lessig claimed he wrote to employees that: "A future start-up with no patents of its own will be forced to pay whatever price the giants choose to impose."

The law professor called Microsoft "a threat" to businesses and the economy as a whole.

The software giant is joined by copyright holders that keep waging their wars against peer to peer and other technological innovations.

Telecommunications giants that aim to lock in users to their networks, for instance blocking the use of VoIP services, form the third front in the war for freedom.

Lessig called upon both individuals and the open source movement to rise up against this threat. Otherwise "the right to innovate will be a blip."

Individuals have to become part of the public debate as well as support organisations that are pro-innovations to prevent this from happening.

There are signs however that Lessig's doom scenario can be prevented.

Several commercial parties in the high tech industry have put the power of their patent portfolio behind one or more open source solutions. IBM has pledged to use 500 patents in the defence of open source, and Sun Microsystems put 1600 patents behind OpenSolaris.

Companies including Computer Associates and Novell have said they are consider following suit.