- There never has been a patent lawsuit against Linux. Never.
- Linux has excellent intellectual property vetting.
- Linux has thousands of high-quality, dedicated programmers.
- Linux creates a robust, secure computer operating environment.
Especially the first part is very promising: with companies like Red Hat, Novell and IBM you certainly have all kinds of companies you could aim at to sue: if you want the big money go after IBM, if you want smaller but still enough money, go after Red Hat.
Still, no one tried to get money out of it – and there are patent processes all the time. Microsoft has to fight many of them, and already lost the one or the other!
But even if Microsoft would try to get after Linux, the OIN would come to rescue – and it is pretty clear that they have the power:
In less than a year, OIN has accumulated more than 100 strategic, worldwide patents and patent applications that span Web / Internet, e-commerce, mobile and communications technologies.
Afaik these patents are quite heavy, and not just “some” patents: the e-commerce patents donated by Novell are highly valuable and make it very difficult for anyone to attack something covered by the OIN without committing suicide at the same time.
Of course, other answers are also quite valid: Linus Torvalds mentioned that all really operating system relevant patents were filled in the early days, long before Microsoft was even founded. And many of the patents belong to large companies like IBM, NEC, Philips and Sony – companies which also take part in the OIN. Oracle sees the importance of the OIN, btw.
I don’t think that a company starting the patent war would have too many friends – and patent wise Microsoft may be a big player, but there are many more much bigger players.
Speaking about Microsoft, I would like to add another quote. The claims about Linux patent violations are not new: in 2004 Microsoft already stated the Linux violates 283 patents. Microsoft based these claims on a study – and the author of that study, Dan Ravicher, quickly responded that Microsoft should be very careful speaking about patent violations:
There is no reason to believe that GNU/Linux has any greater risk of infringing patents than Windows, Unix-based or any other functionally similar operating system. Why? Because patents are infringed by specific structures that accomplish specific functionality