On the free market, there would therefore be no such thing as patents. There would, however, be copyright for any inventor or creator who made use of it, and this copyright would be perpetual, not limited to a certain number of years. Obviously, to be fully the property of an individual, a good has to be permanently and perpetually the property of the man and his heirs and assigns. If the state decrees that a man’s property ceases at a certain date, this means that the State is the real owner and that it simply grants the man use of the property for a certain period of time.
—
Murray Rothbard
http://www.ccsindia.org/ccsindia/lacs/7patents_copyrights.pdf
