What is fair use is basically what a court is going to consider fair under all the circumstances, including general practices in a particular environment. News reporting gets a much wider area of permissible fair use than other areas because of the public importance of unfettered news reporting and free speech to a free society and to ability to criticize the Government and others.

Section 107 of the Copyright Act contains a list of the various purposes for which the reproduction of a particular work may be considered fair, such as criticism, comment, news reporting, teaching, scholarship, and research. Section 107 also sets out four factors to be considered in determining whether or not a particular use is fair:

The purpose and character of the use, including whether such use is of commercial nature or is for nonprofit educational purposes

The nature of the copyrighted work

The amount and substantiality of the portion used in relation to the copyrighted work as a whole

The effect of the use upon the potential market for, or value of, the copyrighted work

The distinction between fair use and infringement may be unclear and not easily defined. There is no specific number of words, lines, or notes that may safely be taken without permission. Acknowledging the source of the copyrighted material does not substitute for obtaining permission.

One test gaining traction is whether the use is transformative, so that it is taken as part of something different than what it was. So a picture being used in a news article is not being used just as a picture and is usually considered transformative enough. If, on the other hand, you just duplicate the picture without anything else, that is not transformative, it is simply wholesale taking, akin to theft, and is probably not fair use.

Bottom line: This is probably OK, provided you take no more than you need and that you transform by offering more than what you take AND that it really is news commentary, as most blogs are.