Copyright is often so complicated. Fixed dates are easier than year of death + N years, because in some cases an author's death date isn't public. You end up wi

Copyright is often so complicated. Fixed dates are easier than year of death + N years, because in some cases an author's death date isn't public. You end up with works which are technically public domain, but which can't be safely used because if you want to avoid any risk of being sued, you have to assume the worst case. Perhaps the author was young when it was created and lived to be 110. Note also that the US 1923 rule applies to the date of publication: works that were created earlier may not have been published until much later. This typically happens with photographs. Edit: and don't expect stock images sites to tell you when an image has fallen into the public domain. They will go on issuing licenses forever. The licenses are bogus, but there don't seem to be any legal repercussions.