As a qualification on one of SEAROSSs remarks, I wish to point out that the term required by the Berne convention, at the time the extension act was signed, was life plus fifty, and may still be. There was, and is, no outstanding treaty to which the US is a party which requires a term of life plus 70. As in the case of environmental and labor laws, so in the case of copyright laws "harmonization" and "trade" have begun to look like excuses for interested parties to push through legislation that can't be defended on the merits.

It is true that the European Union (not the Berne Union) changed to life plus seventy beginning in 1993 or so. This was supposedly in the interests of "harmonization" but even in this case "harmonization" was a fairly flimsy excuse. Most European countries at the time had a term of life plus fifty. So far as I know only Germany (life + 70), France(life + 70 at least for some copyrights), and Spain(life + 60) had longer terms. Spain had reduced its term by 20 years sometime in the past. My hunch is that Spain probably would have finally come down to life plus fifty. The life plus seventy term which was used in Germany and France had originally been justified as a temporary measure to allow rightsholders extra time to make up for wartime losses. Now, suddenly, this supposedly temporary extension has been declared an international standard!

The European extension is discussed in this book review by Richard Morrison.

T.