What's in the public domain?

Note: I live in the US, and so this post is US-centered. Different laws apply in different countries.

The recent discussions on copyright, due to their origin, have mostly focused on "fair use" and technology's impact on copyright law. But if a work is in the public domain, it is free to be used in any way anyone likes, without the need to get anyone's permission.

In genealogy we read source material of various age, and the issue of public domain can arise. There is some confusion though about what is in the public domain, due partially to recent court decisions revising the code, and partially due to different laws being in effect depending upon when a work was written, and where.

I don't work somewhere that understanding copyright law is part of the job description, but a colleague a couple days ago told me he was certain that it no longer mattered when the author died, it was a flat 95 years after creation. This is wrong, but it is understandable why they might think this. There has been a lot of media about corporate copyright, and work-for-hire now lasts for 95 years. Another colleague in the discussion claimed that Disney is actually trying to argue that some of their characters were created by Walt Disney, and not by the company, so that the clock starts when Disney died in 1966. I haven't verified this, but it sounds like a smart business move, for if they are successful, Mickey Mouse won't be public domain until after 2036 (1966+70), instead of 2022 (1928+95). Yielding an extra 14 years of profit.

The Intellectual Property Officer at Cornell University creates an annual chart detailing what is in the public domain as of January 1st of the current year. It depends on factors such as whether the work was published, or unpublished, with notice or without, where, and when. But the chart does a great job in my opinion of simplifying it as much as it can be simplified, and still cover all contingencies.

Note: all my comments regarding length of copyright terms in this post come after reviewing the chart linked above. It's been 12 years since I had any formalized training on copyright law, and that was only one college course, though I do try to follow news stories about related issues.