Ermm.. yeah they can be.
Check out the Digital Millenium Copyrights Act. Its upto the author as to how he wants to license his work. For eg. my blog is creative commons.
But yeah its definitely hard to enforce them.
Hi Guest we just wanted to alert you to a major change in the forum. We will no longer be allowing the posting of outgoing links. Please use the attachment feature to attach media to your posts.