Ask HN: Ramifications of violating patents with open source

I'm curious what damages would be if you released an open source project that violated patents. I've found info about cases where this happened and the project shut down or was granted a royalty-free license but not anything about it being brought to court. Obviously there would be the expense of defense. Wouldn't monetary damages be based on losses? Wouldn't it be the burden of the patent holder to prove damages?