… or at least way too long. Ben White of the British Library gave a really good illustration of this during his presentation at the EuropeanaConnect workshop on Extended Collective Licensing that took place in Luxembourg over the last two days.
On one of his slides he showed the results of a recent study on the commercial availability of print publications that the BL had done. For this study they took 10 random publication from each decade between 1870 and 2010 and checked how many of them are commercially available today:
Full presentation available here
The result is rather striking: there is a rapid drop of commercial availability after (or rather during?) the first 10 years after a work has been published. This indicates that for the majority of all publications copyright protection is way too long. The fact that commercial availability of the surveyed works starts to increase again after seven decades (when works start to appear in the Public Domain in some jurisdictions, and are subsequently offered by print on demand services based in these jurisdictions) also shows that the current, excessive length of copyright protection is not only unnecessary but harmful to society since it leads to reduced commercial availability of older works and thus deprives the public of access to them.
If you combine this insight with recommendation of the Public Domain Manifesto you have a strong argument for a drastic reduction of the term of protection.