One of the most common questions that comes up concerning copyright is “When do I have to ask permission to quote from someone else’s writings?” The answer to that question is closely tied to an understanding of “fair use.” Unfortunately the law itself does not lay out an easy-to-follow definition of how much you can and cannot quote without asking permission. However, it does lay out four criteria to take into consideration when making that determination. (1) The character of the use, including whether it is for commercial or non-profit use. (Is the use going to result in some income to you, or is no profit involved? It’s more likely to be fair if it’s nonprofit.) (2) The amount of material used in relation to the work as a whole. (Have you pulled out the essence of the work or just incidental portions, such as an anecdote?) (3) The nature of the copyrighted work, including how it is typically used. (Are you quoting a paragraph from an article or two pages from a three-volume set?) (4)And finally, what effect is your using the material going to have on the potential market for or value of the copyrighted work? (If it diminishes the value, then the use is not fair.)
Since the fair-use provisions don’t lay out a clear path for the author, I recommend that you study the four criteria above and then use your common sense to ask if it is fair use. You can also ask yourself if you would want to be asked for permission if the quotes in question came from your work. You do always need permission to quote something in its entirety—such as a full article, story, or poem.