Actually, the free market is a bit of a contradiction in this respect. You are right: a free market doesn't have artificial restrictions like patents, copyrights, or trademarks. On the other hand, the free market also depends upon property rights. Patents, copyrights, and trademarks are exactly that -- property rights. Unfortunately, this contradiction is going to become more and more acute as these intellectual properties (and yes, I hate that term) become less and less entangled with their physical counterparts.