Despite the fact that ideas sell for big money in the book publishing industry, it's still difficult to fully protect these ideas. Traditionally, common law stated that ideas set forth in published, authored works were safe for the general public to expound upon. This, of course, means that ideas or premises from legendary tales published in decades past would theoretically be perfectly legal for authors down the road to pick up, provided that specific characterizations or words were not duplicated.
Copyright law protects a specific expression of ideas, rather than the actual ideas themselves. Under the law, specific words or images expressed by an author are solely qualified for protection in an infringement case, in which a copier of such literary components can be found guilty of copyright infringement.
An author's first step in protecting her ideas is to draft a contract. This is a professional practice between author and agent or author and publisher, for such contract of intent could possibly serve as evidence in the event of idea misappropriation.
One form of protecting secrecy or confidentiality discussed between an author and an agent, editor or publisher is to sign a non-disclosure agreement. Such an agreement simply states that the parties involved will not disclose ideas that the author meant for publication, outside of situations determined per the contract. non-competition agreements may also be applicable to relationships between the author and relevant parties. This protects the author in the event that one party should attempt to compete with other parties involved.
In certain cases, in the dreaded event that an author discusses (pitches) a story idea with an editor, only to find that the editor then pitched the idea to a publishing firm as his own, the author may be protected by the right to sue for idea misappropriation. In such cases, the author would need to call upon a contract, perhaps an unspoken contract, whereby the editor or publisher agreed to pay for the idea in question, as it was originally submitted by the author for purposes of his personal enterprise.