I frequently receive inquiries about the effect of the United States Copyright Law on genealogical research. The questions arise in the context of saving off images of various online resources, printing family history books and articles and copying documents for research. Unfortunately, copyright law in the United States (and elsewhere for that matter) is extremely complicated. The best and most concise summary of nearly all the possible iterations of questions about the application of the copyright law is a publication from the Cornell University Library called the Copyright Information Center. Here is a screenshot of part of the website.
It is important to understand that copyright law is intended to benefit the author (creator), however, the law has expanded over the years to primarily benefit commercial interests. If you study the Cornell University Library Copyright Information Center document, you will see a lot of changes have occurred to the law since 1923.
You might notice that I use the words "probably," "possibly," and "may not be" a lot in talking about copyright law. That is because copyright law is made up of two main components: the legislative or statutory law, i.e. that contained in Title 17 of the U.S. Code and all of the cumulative Federal Court decisions that have accumulated over the years. Most of the "law" pertaining to copyright is contained in the thousands of Federal Court decisions construing the law in individual cases. No one can really know for sure what the law is without understanding how the Courts have ruled on a particular subject. This means that it is impossible to make an absolute statement about anything pertaining to copyright. This is a very normal situation for lawyers and those dealing with the copyright law, but it is unsettling and difficult for non-lawyers. At best, even after years of involvement in copyright law, anyone, including attorneys can only make educated guesses about how the law will be applied in any given case.
I am not writing this post in a vacuum. I have addressed this issue many times in the past. Here are a few of the many posts I have written. Rather than repeat myself, I would suggest reading some of these posts.
Can institutions claim a copyright to their collections?
A long discussion about copyright
Copyright and Plagiarism -- What is the difference and why is there a difference?
There are a lot more posts, but this is enough to get you started. You are certainly welcome to ask copyright questions in the comments to this post. But my answers will probably be vague and not very satisfying.