PJ going against guidelines laid out by Tolkien??

[anduin]

I found this article at TOR.N. In the third column, second paragraph is says:

Factoid: Tolkien sold the movie rights to his work in 1971 and laid down strict guidelines for their use. None of his characters could be used in scenes that were not in his books.....

Isn't PJ going against those guildlines when he puts Arwen (just one example!) in scenes where she does not belong according to the book? And what of adding characters to the movie that never existed in Tolkien's books at all like Lurtz?

How were they able to get around these guidelines that were specified by Tolkien himself in case a movie was ever made?