Timothy Taylor writes,

The Milgrom, Levin, and Eilat argument is also intriguing because it points out an inherent conflict between property rights and innovation. For example, those who invent something today and seek out a patent must often be concerned that they are potentially overlapping with other patents that have already been granted to others. In some cases, the property rights of already-existing patents can choke off innovation from new competitors. As another example, when many people own property rights to many different plots of land, it may be difficult for a new use of that land to arise–whether it be a nature preserve or a natural gas pipeline–because the existing splintered property rights make it difficult to negotiate for an alternative use of the land. Property rights and market exchange are excellent at finding efficient ways for existing uses, but when it comes to certain kinds of change and innovation, they can sometimes pose drawbacks.

Taylor refers to a paper that looks at radio spectrum as a common-pool resource. The quoted paragraph suggests that ideas also can be viewed as a common-pool resource.