The parents, from the Colchester area, have 'refused to accept' a judge's finding in June that their son was injured whilst in the care of either or both of them when he was less than a year old.
But today Appeal Court judges boosted the parents' fight for their son back when they ruled that documents in the case should be disclosed to a top expert at London's world-renowned Great Ormond Street Children's Hospital.
The consultant will now carry out a fresh examination of the boy which his parents hope will exonerate them.
The events that devastated the well-off family began when the couple took their baby to their GP who found him 'febrile', off his food and flushed. He was prescribed antibiotics.
A few days later he was taken to hospital where tests indicated an acute brain haemorrhage.
Doctors advised that the possibility of a non-accidental injury had to be considered and emergency steps were taken to protect the boy.
And, in June, Judge O'Brien ruled at Chelmsford County Court that, on the balance of probability, his injuries were non-accidental and occurred whilst in the care of either or both of his parents.
That was despite his finding that the family appeared 'perfectly well-adjusted' with the couple 'mutually supporting' each other and enjoying 'close family ties and family stability'.
Judge O'Brien had described the family unit as 'remarkably problem free, with no marital, health or financial problems'.
Today at the Appeal Court, Essex County Council's lawyers did not resist the parents' bid to have the youngster re-examined by the Great Ormond Street specialist to whom all documents in the case will now be disclosed.
Mr Paul Hollow, for the parents, told Lord Justice Thorpe and Lord Justice Mance their objective was to obtain the expert's opinion and to re-open the issue of how their baby's injuries were caused.
STRAND NEWS SERVICE