A statement from Joe McGinniss worth reprinting:
Bottom line: not only my editor, but Random House attorneys verified every source, in some cases speaking directly to the sources themselves. I have dozens of hours of recorded conversations. Random House attorneys listened to them all, then made an independent judgment about the trustworthiness of the sources. No material from an unverified source is included in the book.
Many details were omitted for that reason. Obviously, any writer would like to be able to name every source. In this case, the climate of fear the Palins created in and around Wasilla made that impossible. After seeing how Sarah reacted to my moving next door, many people became afraid for their own safety and said they’d talk to me only if I guaranteed confidentiality. When I felt I had to, I did. Anonymous sources have a long and honorable tradition in U.S. journalism. Look at Woodward and Bernstein and “Deep Throat.” Just last week, the NY Times had a story about the Mets third baseman and quoted an anonymous source. In twelve books written over 42 years, I’ve never been through a legal vetting like this one. It lasted for months.
The Dish 