Birmingham City Council has been forced to scrap plans to end care packages for 4,000 adults after the decision was condemned by a High Court judge.

Mr Justice Walker said the authority had failed to consider whether there was any alternative to the “potentially devastating” cuts.

He warned that councillors “failed to address the right questions” when they agreed a wide-ranging budget cuts at a full council meeting on March 1, and when the Cabinet backed specific changes to adult care two weeks later.

Representing the authority in a London court hearing, barrister Andrew Arden QC confirmed that the council would continue to provide care to all the affected adults.

It means the authority will need to find the £15 million it had planned to save this year as a result of the changes, which would have limited care packages to adults whose needs were assessed as “critical” - excluding 4,000 people whose needs are judged to be “substantial”.

However, while the court ruling overturns the decisions made in March, it does not prevent the authority from making cuts in the future as long as it does so legally.

Officials warned that savings would still be made to adult social care - following a new consultation.

Peter Hay, strategic director of adults and communities, said: “We welcome the judgement, which has given us greater clarity with regard to the Disability Discrimination Act (DDA), and we will now need to re-run the consultation and make decisions about adult social care consistent with the need to analyse the potential impact on disabled people and our compliance with the equality principles set out in law.

“In the meantime, people will continue to receive services to meet needs that have been assessed as substantial and critical.”

He added: “A report will be brought back to our cabinet members to enable them to decide how the council will meet adult social care needs in the future.

“The original dilemma between reducing services in different areas remains. There is no new money as a result of the judgement and hard choices about meeting growing needs with fewer resources will have to be made by local authorities.

“As this judgement clearly acknowledges, councils can only control spending by setting eligibility criteria.”

In his judgement, Mr Justice Walker said: “The failure to ask the right questions must, to my mind, lead to the conclusion that the decisions of 1 and 14 March 2011, so far as concerns the New Offer for Adult Social Care, were unlawful and cannot stand.

“Moreover, even if members were able to form some sort of opinion as to the broad impact of the move to “critical only”, there was not in the material prepared for the meetings any assessment of the extent to which such mitigating factors as were mentioned would or not reduce the potential severity of the proposed move to “critical only”.”

He added: “I conclude that there was a failure in the material prepared for consideration on 1 and 14 March to address the questions which arose when considering whether the impact on the disabled of the move to “critical only” was so serious that an alternative which was not so draconian should be identified and funded to the extent necessary by savings elsewhere.”

And he said: “Just as the decision making process failed to address the right questions, the same is true of the consultation process.”