On the issue of copyright and fair use, we refer to the article by Electronic Frontier Foundation
The Bloggers' FAQ on Intellectual Property addresses issues that arise when you publish material created by others on your blog.
Questions About Copyright
I found something interesting on someone else's blog. May I quote it?
Yes. Short quotations will usually be fair use, not copyright infringement. The Copyright Act says that "fair use...for purposes such as criticism, comment, news reporting, teaching (including multiple copies for classroom use), scholarship, or research, is not an infringement of copyright." So if you are commenting on or criticizing an item someone else has posted, you have a fair use right to quote. The law favors "transformative" uses — commentary, either praise or criticism, is better than straight copying — but courts have said that even putting a piece of an existing work into a new context (such as a thumbnail in an image search engine) counts as "transformative." The blog's author might also have granted you even more generous rights through a Creative Commons license, so you should check for that as well.
What is fair use?
There are no hard and fast rules for fair use (and anyone who tells you that a set number of words or percentage of a work is "fair" is talking about guidelines, not the law). The Copyright Act sets out four factors for courts to look at (17 U.S.C. § 107
- The purpose and character of the use. Transformative uses are favored over mere copying. Non-commercial uses are also more likely fair.
- The nature of the copyrighted work. Is the original factual in nature or fiction? Published or unpublished? Creative and unpublished works get more protection under copyright, while using factual material is more often fair use.
- The amount and substantiality of the portion used. Copying nearly all of a work, or copying its "heart" is less likely to be fair.
- The effect on the market or potential market. This factor is often held to be the most important in the analysis, and it applies even if the original is given away for free. If you use the copied work in a way that substitutes for the original in the market, it's unlikely to be a fair use; uses that serve a different audience or purpose are more likely fair. Linking to the original may also help to diminish the substitution effect. Note that criticism or parody that has the side effect of reducing a market may be fair because of its transformative character. In other words, if your criticism of a product is so powerful that people stop buying the product, that doesn't count as having an "effect on the market for the work" under copyright law.