The defense of "intellectual property rights" necessarily requires empowering government to regulate and control the use of real property. I can own a computer, printer, ink, and paper, yet thanks to intellectual property law, I am prohibited from combining my property as I see fit. No one is deprived of their life, liberty, or property by my action of printing content, yet under the theory of intellectual property, doing so is criminalized.
Another glaring problem with the concept of intellectual property is that it allows artificial scarcity to be created through the initiation of force against those who duplicate an idea even when no damage is sustained by the original.
Hans-Hermann Hoppe, in "A Theory of Socialism and Capitalism" states the following:
"[O]nly because scarcity exists is there even a problem of formulating moral laws; insofar as goods are superabundant ('free' goods), no conflict over the use of goods is possible and no action-coordination is needed. Hence, it follows that any ethic, correctly conceived, must be formulated as a theory of property, i.e., a theory of the assignment of rights of exclusive control over scarce means. Because only then does it become possible to avoid otherwise inescapable and unresolvable conflict."
The concept of intellectual property rejects actual scarcity as a prerequisite for ownership and attempts to impose artificial scarcity in order to prevent goods from becoming superabundant. No examples of intellectual property can be observed in nature (unlike real property) and it must be recognized that the concept is one of social engineering. It is assumed by some (falsely in my opinion) that government protection of an unnatural monopoly on information must be maintained in order to incentivize productive research and invention, but this theory ignores the vast amount of research and development that has occurred in the open-source sector.
Even if there is a utilitarian argument for protecting intellectual property, doing so necessarily requires violating the natural real property rights of individuals and invariably leads to a police state that resorts to invasive spying in its attempts to ferret out those who choose to copy and paste rather than pay for permission to recreate information. I know that I'm probably in the minority on this one, but I can't square the concept of intellectual property with libertarian ethics and the non-aggression principle.