Campaigners have won a High Court challenge over proposed changes to children's heart surgery services in England.
Save Our Surgery (SOS), which is trying to stop the closure of the heart unit at Leeds General Infirmary, argued the consultation process leading up to the changes was "unfair and procedurally flawed".
On Thursday, Mrs Justice Nicola Davies, sitting at London's High Court, ruled that the challenge must succeed - but what the victory means for the future will be decided at a later date.
An SOS statement said: "This judgment is in itself a victory for the people who fought to keep children's heart surgery services in Yorkshire, and to challenge what they knew to be a flawed and unjust process."
SOS spokeswoman Sharon Cheng said outside the Royal Courts of Justice in London that the ruling did not necessarily mean the Leeds heart unit was saved, and much would depend on what orders the judge decided to make when the matter returns to court later this month.
One possibility is that the judge will order fresh consultations, which could throw plans for the reorganisation of children's heart surgery around the country into delay and disarray.
Ms Cheng said: "We have won this case on every point.
"It doesn't necessarily mean the heart surgery is saved, but fresh reconsideration will have to be given as to what is to happen next and the fight will go on.
"We knew it was time to fight because of the strength of feeling of families.
"The campaign started small, like David and Goliath, then grew and grew out of all proportions."
SOS represents a large number of residents in the Leeds area. Nearly 600,000 people signed a petition against closure.
Children in the area will have to travel to Newcastle or Liverpool for surgery if the Leeds unit is closed.
The legal challenge stems from a decision last July by the Joint Committee of Primary Care Trusts (JCPCT) that paediatric cardiac surgery should be concentrated at fewer, larger sites to improve standards across the country.
At a recent hearing, JCPCT lawyers argued by the consultation process was fair and not open to legal challenge - but today the judge ruled the process fatally flawed.
The sites currently chosen to stay open are at Bristol, Birmingham, Liverpool, Newcastle, Southampton and two London centres. Facing closure are the Leeds site and units at Leicester's Glenfield Hospital and London's Royal Brompton. The Brompton lost an earlier legal challenge to the proposals.
Philip Havers QC, appearing for SOS, argued the consultation process was unlawful because of a refusal of the JCPCT to release information that could have helped the Leeds General Infirmary better make its case for survival.
The QC said the Kennedy Panel, a group of experts set up to advise the JCPCT, produced "sub-scores" measuring the quality of service at each centre according to various criteria.
But the JCPCT chose only to look at the panel's total scores, and "bizarrely" refused to disclose the sub-scores to consultees until the consultation was over.
Mr Havers argued the sub-scores were crucial. He said if the Leeds hospital chiefs had known how they had been marked they could have made submissions to improve their total score and might have avoided ending among the bottom three centres earmarked for closure.
In her judgment, the judge said Leeds were the most affected by the scoring system because they came bottom of the ranking.
She ruled: "As the scores were relevant to the assessment, the breakdown of the scoring should have been disclosed to the centres whether or not the JCPCT proposed to look at it.
"If there is a public law duty to make information available to a consultee disclosure cannot be denied simply because one party does not wish to look at that information."
Hospital bosses in Newcastle were "disappointed" that there will be further delays before the review is implemented.
In a statement Newcastle upon Tyne Hospitals NHS Foundation Trust said: "We remain confident that the original decision will in due course be upheld and the Freeman Hospital will be one of the designated centres providing specialist children's cardiac surgery, for which our performance and very high quality is recognised internationally.
"Newcastle Hospitals gives reassurance that our first and foremost consideration will remain the interests of children and their families under our care and we will not allow delays in the review process to compromise the quality of our excellent service."