Ian Gay, 39, and his wife Angela, 40, from Halesowen, West Midlands, were released from custody on conditional bail after serving 15 months of a five-year prison sentence for manslaughter.
But the judges ordered that they must return to court later in the year to face a retrial. After the ruling the couple said they were looking forward to returning, and standing outside the High Court in London they continued to protest their innocence: "We now know for certain what we knew all along - that Christian died of natural causes... Yet again we protest our innocence and hope that one day soon true justice will finally be done."
Lord Justice Richards, in the lead judgment, ruled that if members of the jury had heard fresh medical evidence supporting an alternative hypothesis for the cause of Christian Blewitt's death they might have acquitted the couple.
During the appeal hearing, Dr Glyn Walters, a retired expert in chemical pathology, argued that it was possible that Christian died from natural causes, rejecting the conclusion that his condition was caused by the ingestion of salt.
Christian died in hospital four days after being found unconscious in his room on 8 December 2002 at a £500,000 house where the wealthy childless couple then lived in Bromsgrove, Worcestershire.
In January last year the Gays were tried for Christian's murder but despite their denials of any involvement in his death were found guilty of manslaughter.
Mr Gay, a former engineer, and his wife, a £200,000-a-year insurance actuary, always said they loved Christian and his younger brother and sister, who had been placed with them for a trial period pending adoption.
Defence lawyers argued in the appeal that the jurors were presented with just two options - either the couple murdered Christian by applying blunt force to his head or were guilty of manslaughter through feeding him salt as a punishment for naughtiness.
Dr Walters argued that the boy was not a victim of salt poisoning and could have been suffering from a rare condition which allowed sodium levels to build up in the body. The condition could explain why Christian - alleged to have been force-fed up to six teaspoons of salt, equivalent to a litre of sea water - had so much sodium in his body.
Lord Justice Richards, sitting with Mr Justice Penry-Davey and Judge Ann Goddard, said they had not lost sight of the fact that the medical evidence, although important, formed only part of the evidence.
The couple, having recently taken on the "immense burden" of looking after three children with a view to adoption, were "in a position of considerable stress". Difficulties they had experienced with Christian had added to that stress.
But this did not alter the possibility that the fresh evidence could have influenced the outcome of the trial. The convictions were "unsafe", the judge said.
Arguing against a retrial, Michael Mansfield, QC, for the defence, said that in such a unique and complex case, the scientific dilemma facing the medical experts could not be solved by asking a fresh jury to "grapple" with it. "There is a very high risk of a further conviction that might be regarded as unsafe because it is a case based in the realms of speculation," he said. But the judges ruled that a retrial should be ordered "in the interests of justice".
The Crown Prosecution Service said it expected a new trial later this year at Worcester Crown Court.
Claims and counter-claims
Christian Blewitt was admitted to hospital on 8 December 2002 suffering from hypernatraemia, an abormally high concentration of sodium in the blood. He died four days later.
At the trial the judge said the only explanations for this condition were "severe dehydration" or a pre-existing metabolic disorder or disease.
The judge said doctors had "ruled out" all possible diseases and disorders that might have caused the high level of salt.
In the appeal, new evidence was cited to provide a possible alternative explanation for the hypernatraemia. The new hypothesis was put forward by Glyn Walters, a medical expert with experience in fluid and electrolyte disturbance.
He disagreed with the prosecution witness's conclusion that hypernatraemia was caused by the ingestion of salt. He based hisanalysis on the fact that had Christian ingested such a large amount of salt there would have been medical signs that his body had excreted a proportion of it. Although there was a high rate of excretion initially that tailed off, it was back to normal rate after 12 hours. He should have gone on excreting salt at this high rate for another 48 hours.
Dr Walters also said it was significant that there was a failure to bring the sodium level in Christian's body down to the normal range. He concluded that the reason for this was a fault in Christian's natural mechanism for maintaining the concentration of sodium in the body, which is controlled by the hypothalamus in the brain.
This could have affected his capacity for drinking water which would have off-set the effect of large amounts of salt in the body.
None of this was considered by the jury at the original trial.
Comments