Can someone copyright a work once in the Public Domain?
No They can copyright new work BASED on the PD work if they make original, creative changes. On a site using public domain works such as WPClipart: I cannot take what is already in the public domain, then claim to have scanned, cleaned-up, tweaked lightness/contrast, etc and then claim I now have copyright on that work. Although the “sweat of the brow” copyright arguement may hold some merit logically (the work put into the aquiring, scanning, etc. should earn the worker something…), it holds no weight legally. Copyright was meant to advance creation, allowing things to be created and profited from yet be built upon… to hoard something already deemed public domain goes against this principle.
