US Copyright

The Congress shall have Power ... To promote the Progress of Science and useful Arts, by securing for limited Times to Authors and Inventors the exclusive Right to their respective Writings and Discoveries. -- United States Constitution

The US is one of a few countries in the world where a copyright (such as those of books) is a property right, not a moral right. Moral rights often last indefinitely. But in the US, copyright lasts for a limited term. Or it was supposed to. ... Or at least Thomas Jefferson wanted it to.

Originally, copyright was for 14 years and could be renewed for another 14. A total of 28 years. But since then there have been several laws passed extending the duration of copyright.

In 1831, the original term was extended to 28 years with a 14 year renewal (42 years total).
In 1909, the renewal term was extended to 28 years from 14 (56 years total).
In 1954, the copyright term was based on the life of the author and wasn't fixed.
In 1976, the term became the life of the author plus 50 years.
In 1998, the term was extended to the life of the author plus 70 years.

So you can see that we've come a long way from copyright lasting 28 years max. Now if you publish something and died the next day, the copyright would still last longer than that. (I should note, the above is greatly simplified. There are some types of copyright, such as work-for-hire projects, that are 95 years fixed. But this is confusing enough already!)

What does this matter? It probably doesn't effect you much, unless you're trying to figure out if a book is public domain--maybe you want to make it available as an ebook or something.

Simple Facts: Any work published before 1923, is now considered public domain.

But after that, things get trickier thanks to the law changing.

If a book was published between 1923 and 1963, and the copyright was renewed in the 28th year, then the book is still protected by copyright. (For example: the Fitzgerald Estate will still be making money off the Great Gatsby film coming soon to theaters. Gatsby was published in 1925.)

If a book was published between 1923 and 1963 but not renewed in the 28th year, then it is now public domain.

You need to check on this. The US Copyright (copyright.gov) website does allow you to search, but their records between this time are a bit spotty. It is best to hire someone in Washington to look at the copyright records in person, if you are curious about a book from this time period.

Anything published after 1963 doesn't have to be renewed at all. Renewals were made redundant. On the one hand, this was good for saving time on paperwork. But it was bad for so-called "orphan" works. Now we often don't know who owns the rights to things--just that someone does and it can't be licensed or re-purposed. I imagine poor abandoned works begging on the street for attention, but the law won't let us give it to them...

I got off track. In answer to the question, "Is this work public domain?":

• If it was published before 1923, yes.
• If it was published before 1963, maybe. 
• If it was published after 1963, no. 

For more in-depth answers to these questions see: Copyright Term and the Public Domain (Cornell University).