The Court of Appeal ruled today that Health Secretary Jeremy Hunt did not have the power to implement cuts at Lewisham Hospital in south east London.
Three judges announced their decision on the second day of a hearing in London.
Supporters of the highly-regarded hospital cheered when Lord Dyson, the Master of the Rolls, sitting with Lord Justice Sullivan and Lord Justice Underhill, gave their decision in an appeal brought by the Government over a High Court judge's ruling in July.
Mr Justice Silber had then ruled that Mr Hunt's move to downgrade A& E and maternity services was "unlawful".
Rosa Curling from law firm Leigh Day, who represented the Save Lewisham Hospital Group said: "We are absolutely delighted with the Court of Appeal's decision today. It confirms what the Save Lewisham Hospital Campaign has been arguing from the start - that the Secretary of State did not have the legal power to close and downgrade services at Lewisham Hospital.
"This expensive waste of time for the Government should serve as a wake up call that they cannot ride roughshod over the needs of the people
