To further complicate matters, CC licenses define peer-to-peer file sharing as "noncommercial" - a position with which the United States Supreme Court has disagreed and is otherwise at odds with U.S. law.Link (Thanks, Luke!)
Huh? The "United States Supreme Court" has said nothing, and, more importantly, could have nothing to say, about whether a copyright owner is allowed to grant freedoms to users for a particular use, such as p2p file sharing. Again, the freedom to grant freedoms is part of what copyright law gives a copyright owner. This freedom is certainly not "at odds with [at least this provision of] U.S. law."