Q. I am writing an encyclopedia article and want to cull some facts from earlier articles on the topic. I will also quote a couple of passages from the same sources. Is there a copyright problem?
Facts are not protected by copyright law. The date or the place of my birth, for example, are facts in which I can not claim any copyright, nor can any person who writes my biography. In so far as you are simply harvesting facts from various sources and repackaging them, no copyright issue is raised.
On the other hand, the expression of a fact can be protected by copyright law. An author would have a copyright interest in a specific sentence recounting my birth, and that sentence can not be directly copied without infringement. So you should avoid copying the expression of the facts that you are harvesting.
One complication of this distinction between fact and expression is the “merger” doctrine, which says that when a particular fact can reasonably only be expressed in one way (so that fact and expression “merge”), no copyright in that expression will be recognized. A plain statement that “John F. Kennedy died in 1963” would be an example — there is little creative about it and the expression really does merge with the fact. On the other hand this sentence — “JFK’s assassination in 1963 was the tragedy that defined the second half of the century” — surely does contain enough original and creative expression to be protected.
If your use of facts gathered from other sources does not copy protected expression, even if it occasionally repeats some uncreative expression that merges with the bare facts reported, there is no copyright issue at all. The citation of the sources from which the facts were gathered is, of course, good academic practice, but it is not required by copyright law.
When you quote or paraphrase a judgment, opinion or estimation, however, you are certainly in the realm of copyright protected expression. If you paraphrase, copyright does not enter the picture, because the expression is not being copied. Plagiarism, of course, might be an issue, and you address it by citing the source. If a direct quotation is used, so that expression is copied, fair use is the exception that prevents an infringement of copyright. The use of small segments of protected expression for the purpose of research and scholarship is a universally recognized instance of fair use and authors rely on it all the time. Only when longer quotations, diagrams, pictures or data sets are copied does it really become necessary to get permission. In doubtful situations, publishers will usually err on the side of caution and want you to obtain permission, even when these citations are probably fair use.