An editorial in the New York Times has been making the rounds, and I felt like weighing in. Most of those I've read agree with me in thinking perpetual copyrights are a very bad idea, including some I often don't agree with, such as Ilya at Volokh. Ilya makes important points about the difference between intellectual property and physical property; when somebody else uses my physical property, they are interfering with my ability to use it, while when someone else uses my intellectual property, I continue to be able to use it freely. If there were a method of duplicating land, we probably would treat the creation of duplicates of already occupied land quite differently than we treat invasion of already occupied land.
I would like to add a point I've made before concerning property rights generally. Any property right is a a monopoly on the use of a resource, enforced by the state. It only makes sense that people should be charged for the state's services in this area, as in some kind of wealth tax. If establishing and maintaining intellectual copyrights were more expensive, with a high minimum fee which increases with time, and a percentage of profits if that exceeds the minimum payment, then allowing long copyright terms, even indefinite ones, would not be as egregious. For one thing, it would obviously raise state revenues. Also, it would reduce cases where copyrights would be held by people who were not bothering to make the copyrighted material available in any form; holding on to an unused copyright would be expensive, so such copyrights would usually be allowed to lapse, allowing others to make use of the material.