When an individual makes a music or movie file available for downloading by others, without the permission of the copyright owner, is that an infringing act? Or does infringement take place only when the file is actually downloaded?
This thorny copyright issue is at the heart of much of the controversy over file-sharing. It’s relatively simple for a copyright owner to prove that a file has been made available for download, but it’s much harder to prove that a download has actually occurred. So if liability attaches to the mere act of “making available,” record labels and movie studios will have an easier time combating file-sharing. [...]
James Gibson, Reproduction, Distribution, and "Making Available", The Media Institute (Nov. 23, 2010), available at http://www.mediainstitute.org/IPI/2010/112310.php.