How do we protect our interests in the agreement, as authors who want to secure someone's life story rights?

You must obtain a life's story rights agreement. What they are talking about (I believe) is reserving the rights to produce a book on tape or the like. However, these are extremely detailed document and entertainment law is a highly specialized area of the law. Consequently, I encourage you to contact a qualified entertainment IP attorney to discuss the details of your matter.

Do not sign the agreement until you have all the rights you want, including the exclusive right to make a film from the book you will write. Language should also be included in the agreement protecting you against claims. Sounds like more negotiation is necessary with the Subject's lawyer. I have handled these types of deals before.

Exclusive rights are often hemmed to a specific medium, such as exclusive rights to print, or exclusive rights to a specific geographic zone (such as North America distribution rights for traditional print). You're involved in contract *negotiations*. So, negotiate! Make your own proposals (such as for indemnification against third-party suits, and a clear clause giving you rights to derivative works), and seek clarification for any clause you don't fully understand. It's silly to sign the first draft of any contract you're offered unless you have some background or experience with the other party, especially when professionals, such as attorneys (who reflexively write contracts in favor of the party who hired them!), are involved. My recommendation? Get your own attorney to review the contract and suggest changes! I and almost all the other attorneys in town who do entertainment law regularly do contract reviews of this sort. And never rush a contract negotiation. Take your time!

The best way to do this is to get a lawyer to write your own contract for you and you present it. If you are paying for something, do not have the other party write the contract. Having your own lawyer should be major part of how you conduct this business. I do this kind of legal work and I can tell you that if you sign a bad contract, there is almost no way for any lawyer to help you. Do not sign, get your own lawyer, have your lawyer write a contract, and present it.