Can I just say that the McCann's are in no way stupid and neither is their lawyer.
If you think they are having a libel case, because 'the book didn't influence the search for Madeleine' then why is there a libel case?
Why take someone to court if there is no evidence?
My opinion is that Amaral's book would have had an impact on any person who may have had evidence about what happened to Madeleine after the case was closed.
Especially those living in Portugal, who would know Amaral and know he was the chief police officer in charge of the case. He would have a great influence on what they thought about the McCann case. Reading that Amaral had concluded that Madeleine had died in the apartment and that the McCann's were guilty of faking an abduction and hiding her body. The TRUTH of the Lie the book was titled, people would tend to believe what he wrote.
Anyone who may have had information about Madeleine or who had taken her would, after reading Amaral's book think twice about what they knew. Think, Amaral says she is dead, what I saw or heard couldn't be of any relevance.