What is a permalink on Flickr and what do you do with it?

Is Flickr's use of Creative Commons valid?

• Creative Commons licenses have been quite popular any time recently, but some uses make me question CC licenses in general and their effectiveness in particular. This is what raises the following questions for me: 1) http://Flickr.com lets photographers attach CC licenses to their photos, but their website enables them to revoke that license from the photo afterwards. Is that legal, as CC licenses are not revokable, actually? What if I have downloaded and used a photo, say for commercial ads, and in the meantime, the photographer changed the license back to "All rights reserved" on Flickr? That did happen for me. What should I do? I cannot prove that the photo was previously CC-licensed. 2) If a photographer releases his work under a CC license on http://Flickr.com, may I download that image from Flickr and use it for whatever this license allows me to do? Or does http://Flickr.com get special rights so that they may impose additional restrictions, just because they are hosting the photo? They require that apps do not cache photos for more than 24 hours, e.g., so can that be valid for CC-licensed photos as well? 3) Lots of applications and websites that use the Flickr API enable the user to view all kinds of photos from Flickr. But may those app publishers really enable the users of their apps to view my "All rights reserved" photos? I don't see that I have granted other parties than Flickr itself such rights by just using the Flickr upload and publish features. Thanks for your attention and time in advance!

• Answer:

  The question suggests that this is Flickr's use of a Creative Commons license. Actually it is the photographers. The fact that Flickr enables them to list these photos as CC on their website is a function, not a license agreement that Flickr itself is offering. And whether or not Flickr enables the revoking of a CC license, it is still the photographer making the change, not Flickr. I would also like to point out that Flickr has their own license agreement with the photographer (or any user of their site/app) that stands outside of the whole Creative Commons license. I'm sure you would agree that a photo can be subject to more than one license agreement. How else would you sell it to multiple clients if you were a professional? The usage by Flickr and its users, as well as the restrictions imposed for that process, all fall under the agreement found in their Terms of Service. It is through this license that people are viewing your photos, even if they are marked All Rights Reserved. A necessary process for them to be able to view them through an online service at all. Your core question is really Can a Creative Commons license be revoked? The answer is no. The author may choose to no longer distribute his own works with a creative commons license attached, but uses that were based on the previous CC license cannot be prevented if they comply with your license at the time of creation. http://www.crucialthought.com/2009/03/03/creative-commons-licenses-cannot-be-revoked/. In this case, Flickr is enabling change from CC license granted to no new licenses being granted, which is a good feature for them to support.