We’ve been trying hard to get to the bottom of the complicated issue of handling photos, other than your own, in the blogosphere. Fortunately, a professor of law at Case Western, Ms. Jacqueline Lipton, PhD, was kind enough to weigh in. Her comments are below, and we’ve amended The Code, to reflect this issue with a simple: We will respect copyright on photos (with a reference to these same notes).
In response to your query, generally it’s wise to always seek permission from the copyright holder if the image in question doesn’t have a license attached describing permissible uses (eg a Creative Commons type license).
Of course, depending on the type of use being made, the reproduction of a photograph without permission could be a “fair use” under the copyright law, particularly if no commercial use is being made of it and it is not interfering with a market for the photograph – which may well be the case on many blogs. Thus, the otherwise potentially infringing use could be excused under the fair use doctrine.
It is important to recognize that the question of attribution is a separate question to copyright infringement. While you should always attribute the source of a picture, copyright infringement is a separate question and you can infringe copyright even if you give appropriate attribution. While many copyright holders will only ask for attribution in return for permission to use the picture, it is NOT a general rule of copyright law that if you give appropriate attribution, you have not infringed copyright. Copyright law deals with acts of copying or displaying a picture, not how it is attributed.