How about 20 years after publication? That would give Harry Potter and the Philosopher's Stone another 5 years. I'm sure JKR could live with that. CJR Tolkien would have to live off the savings of the Tolkien estate, and takings from his own works (The Silmarillion, which he finished off and published over 20 years ago, and some other more recent publications based on JRR's unfinished work).
Less popular authors wouldn't make enough, but they don't make enough regardless. There's very few books which make any real money 20 years after publication, as the chart shows.
The downside would be the moral rights of authors. Some authors are a bit tetchy about their characters being used by other authors. JKR is reputedly pretty cool with fan fiction (she knows her fans will just buy more of her stuff), but some authors would be a bit offended at their characters being used in slashfic, or whatever other weird use people could think of.
On the upside, educators could use it. Sure, there's "fair use", but it's too badly defined to get a definite sense of what "fair" is (for good reasons - a narrow definition would encourage people to abuse it). Teachers and textbook publishers are too stingy to hire copyright lawyers or buy rights, so they just use stuff that's clearly in the public domain. Want to know why textbooks are boring? The lack of public domain materials is one reason (others are listed here: http://www.edutopia.org/textbook-publishing-controversy)
I saw a comment on a similar thread about a month ago suggesting a recurring annual cost for renewing copyright. The formula for the cost would be similar to 2^n-1, where n is the number of years the work has been under copyright.
This would allow popular and profitable works to stay under copyright longer, while allowing less profitable works to enter the public domain sooner.
One problem with requiring people to renew their copyright is that a lot of people will simply forget. There are people who produce hundreds of little pieces every year, each of which generates little revenue on its own. Should they renew their copyright on each and every work at the end of every year? Currently, their works are automatically copyrighted, even if they don't put up a copyright notice.
I think you should wait X years (where X is around 10-20) before that formula kicks in.
The old UK system was the longer of 42 years after publication, or 7 years after the death of the author.
The actual numbers might not be perfect, but this kind of system (possibly with different numbers) would eradicate the downside you mention.
It might be appropriate for different types of work to enjoy different copyright terms. You are probably right in saying that 20 years is long enough for a book, but music might last longer due to covers, remixes etc.
It might be also appropriate to have different events occurring after different terms, rather than simply shifting from owned to public domain overnight - e.g.
Up to 30 years: A copyright holder is pretty much god, save for any parody/fair use etc. clauses.
After 30 years: A copyright holder is bound to accede to "reasonable requests", and cannot place unreasonable conditions or fees on use.
After 50 years: Must be properly attributed, but otherwise it is uncontrolled.
After 100 years: Completely public domain, and you can do what you want;
Covers and remixes are no different than derivative works of books, plays or film. Copyright should be universally applied to all creative works.
That said I do like the idea of a potentially staggered coverage. Perhaps 0-X: monopoly. X-Y: compulsory licensing. Y+: attribution
Particularly because music already enjoys compulsory licensing and it seems to work fine. And attribution seems like the right thing to do, regardless of the age of the work.
I don't mean to claim that covers and remixes are any different, merely that the practice is quite prevalent, meaning that tunes penned by various artists 20-50 years ago are still being heard in the charts today, spurring a resurgence in interest in the original.
The same can only be said of a small handful of authors, whose older books lend their names, and occasionally their stories to new films.
I also agree that attribution is right regardless of age; but over time, without a central rights management authority, it could be difficult to assign proper attribution, leading to the potential for copyright trolling akin to the kind of patent trolling we see today. Perhaps instead of expiry, there should be a time immemorial for copyright.
Less popular authors wouldn't make enough, but they don't make enough regardless. There's very few books which make any real money 20 years after publication, as the chart shows.
The downside would be the moral rights of authors. Some authors are a bit tetchy about their characters being used by other authors. JKR is reputedly pretty cool with fan fiction (she knows her fans will just buy more of her stuff), but some authors would be a bit offended at their characters being used in slashfic, or whatever other weird use people could think of.
On the upside, educators could use it. Sure, there's "fair use", but it's too badly defined to get a definite sense of what "fair" is (for good reasons - a narrow definition would encourage people to abuse it). Teachers and textbook publishers are too stingy to hire copyright lawyers or buy rights, so they just use stuff that's clearly in the public domain. Want to know why textbooks are boring? The lack of public domain materials is one reason (others are listed here: http://www.edutopia.org/textbook-publishing-controversy)