A common claim I've heard by entrepreneurs of the last 5-10 years is a need to acquire "defensive patents". I've always been skeptical of the idea but largely would just nod my head.
If you talk to various silicon valley entrepreneurs you'll hear how little they are actually used.
If the entity suing you is a non-practicing entity, what is there for you to catch them infringing upon? I fear that is the real reason they are non-practicing entities.
When you don't have to worry about mutual destruction caused by your victim, you can extract more capital.
-- Christian Hergert 2013-10-29