Interesting aproach, but we have to translate it into a reality where lobbying has locked up life+50 into a number of international treaties that will take time to change (but MUST in due time, if the public starts to understands how they are being robbed). For the inbetween, I suggest a smart taxation scheme. Most countries have a sales tax or value added tax in the order of 10 to 20 percent. We could now offer two ways of paying that tax, either the normal way, that is, on sales as they are being made, or payment as a much earlier dedication to the public domain, according to some formula similar to that of Robert. Since most works don't have an enduring reputation, most publishers (except those of established classics) will probably go for the short term benefit. To enter the scheme, a registration and a contract with a copyright office will be required. We could try to make the scheme compulsory for DRM-ed works (together with a deposit of an unencumbered copy in a copyright office), since legislation around DRM is still on the drawing table in many countries. Joining the scheme will be (due to international obligations) be voluntarly, but could be made compulsory once these obstacles are taken out of the way; such that life+50 (or 70) will only remain in place for unpublished works, where I have much less trouble with the long term. I will further work out this idea in a document I am working on, called: "Cultural Heritage and Copyright, a misbalancing act"... Jeroen Hellingman. Robert Shimmin wrote:
The sad truth is that when approached from an economic point of view, the optimal length is so short that it seems absurd, and nobody takes you seriously after they hear the result. Here's the analysis:
Let's say that we have a work of enduring reputation, so that the right to publish it is worth a perpetuity of some annual income A. The copyright then has a present value of A/r, where r is the interest rate. We wish to transfer the copyright from the rights holder to the public when the public has paid the rights holder A/r.
The public pays the rights holder A per year, and if this money accrues interest at the same rate r, then (omitting a pile of algebra), then the public will have paid the rights holder A/r after N years, where N=log(2)/log(1+r). Those with some accounting knowledge will recognize that the optimal copyright term at some interest rate is the same time as the doubling time of money at that interest rate:
interest copyright rate term 2% 35.0 yr 3% 23.4 yr 4% 17.7 yr 5% 14.2 yr 6% 11.9 yr 7% 10.2 yr
It's interesting to note that the copyright term of the legislation that started the Anglo-American copyright tradition, the 1710 Statue of Anne, hit this range on the nose with a 14 year term (5% interest). It got the number from the 1624 Statute of Monopolies, which limited royal monopolies to 14 years. In patent law, where the economic disadvantages of too long a patent term are quite clear, most patent offices have kept patent terms in the 14-20 year range, which seems reasonable, looking at the table above. In copyright law, the Continental jurists won the day, and things have gotten out of hand ever since.