When is a movie of a book not a movie of a book?

The recent Bourne Trilogy has really only two elements of the Ludlum books. A spy/agent/assassin and amnesia. Apart from that the movies represent a completely different story. Even the characters are changed. The original Bond books are also completely different.



So, given the Trades Description Act is enforced with sales and product literature - how come it is not applied to movies. Adaptation does not mean a different story. 'Based on' implies a plot similarity.



So, where is the line drawn?When is a movie of a book not a movie of a book?
The filmmakers buy the book and do with what they want with it



look at 1968 Casino Royale, nothing like the book. Look also at most of the later Roger Moore named film, nothing like the books or Novellas they were named after



Anne Rice once said there are her books and then there are movies which have her books titlesWhen is a movie of a book not a movie of a book?
it seems you have way to much time on your hands if your reading books and seeing movies , then complaining about the differences.get over it. with all the problems in the world, maybe you could fixate on something more realistic.When is a movie of a book not a movie of a book?
Sorry to cheese everyone off by mentioning it but the Harry Potter movies have been a big disappointment compared to the books all except for Gary Oldman as Sirius Black.
If a movie is adapted from a book, it tends to follow the story fairly closely, without being a word for word version. If it is based on the book, then the screenwriter has pretty much a free rein in how he/she chooses to get the characters to the end.