I just thought I would reiterate your point about the importance of knowing the law carefully before publishing a public domain work. The law, as you mention, differs from place to place. And it can get complicated.

For example, I believe that, in Australia, the relevant period has been extended from 50 years after the author's death to 70 years after the author's death (I vaguely recall the extension had something to do with the US Free Trade Agreement).

I think the trend is toward extending the period of copyright rather than shortening it. In some countries, the extension of the life of copyright may apply retrospectively (in other words, a book that was once out-of-copyright might now be back in copyright). So it's important to know the currently applicable law.

These differences become important when you are providing the public domain book to a global audience.

For example, say you put up a public domain ebook on your website. The book might be out-of-copyright for readers in Australia but still in copyright for readers in, say, the UK.

You do not want to get into the situation where you might be held to have been authorising infringement of someone else's copyright. An appropriately worded disclaimer, which puts the onus on the person downloading the book to check their local copyright laws, might be prudent.

I have several public domain works on my website at http://www.write-better-english.com (look for “How to Write Clearly” and Fowler's “The King's English” under Resources > Books (full text)). At the bottom of every page of these public domain works you will see a disclaimer that a lawyer-friend of mine suggested I add.

Hope this helps.

Thanks for allowing me to voice this ~ Joyce