A "substantial question mark" hangs over the convictions of four people jailed for killing or harming babies by shaking them, appeal judges have heard.
The four appeals stem from the Angela Cannings case
If the four are cleared at the Appeal Court, about 90 other cases of "shaken baby syndrome" could be challenged.
Defence lawyers are fighting the view that swelling of the brain, bleeding behind the eyes and between the brain and skull are all symptoms of abuse.
They said such medical evidence has been thrown into doubt since the cases.
Far from being child killers or abusers the three men and one woman - convicted of murder, manslaughter or grievous bodily harm - were "loving and supportive", said Michael Mansfield QC.
FOUR TEST CASES
Raymond Rock, of Great Yarmouth, Norfolk, serving life for murdering his girlfriend's 13-month-old daughter, Heidi Davis, in 1998. He insisted she wriggled out of his arms and fell to the floor
Lorraine Harris, 36, of Long Eaton, Derbyshire, jailed for the manslaughter of her four-month-old son Patrick McGuire in 2000. She said the baby became ill and stopped breathing after a vaccination
Alan Cherry, convicted in 1995 of the manslaughter of his girlfriend's 22-month-old daughter Sarah Eburne-Day. He claimed she fell off a stool
Michael Faulder, 34, of Gateshead, jailed for two-and-a-half years in 1999 for causing grievous bodily harm to a boy aged seven weeks. He said he accidentally dropped the baby while trying to put him in his pushchair
In each case jurors had been asked to rely solely on now-discredited expert evidence alleging that the children had been violently mistreated, he said.
Mr Mansfield used the example of Raymond Rock, of Great Yarmouth, who was convicted of murdering his girlfriend's 13-month-old daughter Heidi Davis in 1998, but claims she wriggled out of his arms and fell.
The QC said Mr Rock's trial included evidence from seven experts who used phrases like "I have never seen such severe injuries", "shaken as hard as you can", "nothing short of full-force shaking", and "equivalent to a high-velocity road traffic accident".
Despite leaving no option but to convict, there was no indisputable or objective medical evidence of violent treatment, said Mr Mansfield.
Opposing the appeals, Crown counsel Richard Horwell told the judges that Mr Mansfield's arguments were flawed.
Over the next two weeks the Appeal Court will hear that new evidence suggests the symptoms linked to shaken baby syndrome could actually be caused by a "far lesser threshold of force", such as short falls, vaccinations, difficult births or genetic conditions.
Mr Mansfield said: "This is not back-room biology by a few cranks.
"These are highly reputable experts from different institutions in the UK and some in the US who therefore do not espouse something which is fanciful."
The question the court faced was whether jury convictions were safe when there were now alternative hypotheses to those relied on by experts, he said.
The appeals stem from a review ordered after Angela Cannings' convictions for murdering her two baby sons were overturned.
Mrs Cannings was cleared after judges ruled that no-one should be prosecuted solely on the basis of medical opinion which was disputed between experts.
The review, ordered by Attorney General Lord Goldsmith, involves some 300 infant death convictions.
The hearing could also affect hundreds of other cases where a parent - usually the father - has been denied access to a child on the basis of allegedly violent treatment.