The couple say Goncalo Amaral has defamed them with his 'absurd and deeply hurtful' claims that Madeleine died in an accident and that they concealed her death.
Mr Amaral has repeated the claims about Madeleine, who vanished aged three while the family were on holiday in Praia da Luz in 2007, in newspapers, documentaries and in his book about the case, titled The Truth About The Lie.
The McCanns say the former detective, who was forced off the case after criticising British police, has caused 'indescribable devastation and suffering' to their family and his claims have 'obstructed' the search for their daughter.
source said the McCanns could be forced to
give evidence in court in their action
against Mr Amaral ? presenting him with a
stage from which to attack the couple.
publisher, Mario Sena Lopes, said he was
?looking forward? to his day in court.
seeking a British publisher for his book
after selling 250,000 copies on the
Continent, including 175,000 in Portugal.
version has already been produced for
McCanns also want to make sure a documentary
produced by Mr Amaral for Portuguese TV does
not win a wider audience.
defamation case, lodged yesterday in Lisbon,
alleges that Mr Amaral has damaged their
reputation ?causing indescribable
devastation and suffering? and put in danger
the well-being of their children, twins Sean
and Amelie, four, and particularly
was forced off the inquiry in October 2007
for criticising British police.
partly responsible for making the McCanns
arguidos, formal suspects, in the case.
claims Madeleine, then aged three, died in a
?tragic accident? in the holiday flat on the
night she disappeared.
has never claimed that heart surgeon Gerry
and GP Kate, of Rothley, Leicestershire,