The sad part of it is, governments are increasing copyrights against the advice of their copyright offices, without considering the choices which will have the best impact on their country (which government has seriously taken advice on the "optimal" length of copyright?). These decisions are adversely affecting consumers every day but they're hurried through because nobody cares.
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. -- RS