I was asked to post this on my blog, a copy of a post from the mono mailing list. This is slightly edited from the original:
The fear that people have on Mono's legal issues apply equally as well to everything else. Let me explain. Sun owns various patents on Java, and they might just feel at some point threatened enough to use them as a weapon against open source. In the same way people feel that Microsoft might pull that trigger. Just to put things into a different perspective: Sun has litigated over Java in the past (against Microsoft) over a contractual dispute and has done threatening legal moves against JBoss at some point (which I do not claim to understand) over bits of J2EE. If Java on Linux became a threat to Sun, would they use their patents? I do not know, and I hope not. Am only illustrating the point, just like other people have vehemently illustrated the Microsoft patent risk before. There is nothing in Java that makes it any safer than Mono at this point. We do not have any guarantees, any written statements, any guarantees that Java on Linux will not be sued under certain conditions. Microsoft has granted RAND+Royalty Free licenses to any patents they might own that are required to implement the ECMA 334/335 standards. So at least our core VM, classes and compilers are safe from any litigation from *Microsoft*. Now, pay attention to the above, because it is important. The fact that Microsoft has given access to any patents they might hold on .NET does not mean that a third party that has a patent that is required to implement ECMA (or Java) will grant that license. Why does this matter? Because we just do not know if someone has a patent on pieces that Java and .NET implement. There might very well be one that we are not aware of. The patent might remain sleeping for a few years before someone decides to profit from it. And the above is important. It is important because even with a fully re-engineered virtual machine, runtime system and the rest, we do not know if you will not be infringing on a Sun, Microsoft or third party patent. With the current patent situation, it is probably impossible to ask small startups or individual developers to do a patent review before they make decisions on how to implement their software, only very large companies might afford it, and believe me, even with vast resources, you might be taken to court by an unknown (Eolas patent for example) or by a law firm who focuses on purchasing dormant patents and litigate them. Nat used to say "If you write a thousand lines of code, you are violating someone's patent today". The picture is not pretty for anyone in the software industry. But this is similar to what happens to biology students: on their first four semesters as they learn about all the dangers, infections, vectors for infections and bacteria, they stop eating everything, they start washing their hands with special products, they double clean their utensils, they wash their fruits ten times a day. Two years later they are eating food with their bare hands again.