One of the Portuguese lawyers of the McCanns, Rogerio Alves, told the newspaper Diario de Noticias: "What has to be done will be done in due time."
Another member of their legal team, Carlos Pinto de Abreu said such a move was "technically possible" but would be difficult in practice. Because, it would mostly rely on the McCanns being able to prove that Portuguese police had failed to act on information which could have led them to Madeleine.
Some witnesses have complained that Portuguese police never returned their calls or investigated their sightings. But, simply on that ground they can't sue the police, as it is very very diffucult to prove that it was intentional.
There has been speculation that the Madeleine case could be closed by Portuguese police, as early as Christmas. via DailyMail