Duke University’s Center for the Study of the Public Domain has posted an analysis of which books would have entered the public domain on 1 January 2014 if the maximum copyright term remained at 56 years. The change to 70 years protection from the death of the author became effective in 1978 due to the 1976 Copyright Act. The article notes that European copyright law is more user and library friendly than current US practice.
The article is here.