The government has lost the latest stage of its fight to prevent publication of an internal civil service assessment of risks posed by the controversial NHS reforms.
A Department of Health appeal against an order by the Information Commissioner to publish the "transition risk register" was thrown out by a tribunal.
Officials argued disclosing the dossier would inhibit civil servants from speaking their minds to ministers in the future.
The Information Rights Tribunal upheld the commissioner's ruling that the November 2010 document should be disclosed.
The call for the register to be published was made by former shadow health secretary John Healey.
In response to the tribunal's decision he said: "The judgment backs the public's right to know about the risks the Government is taking with its NHS plans."
The Department of Health will await the tribunal's full decision before deciding whether to appeal, but Mr Healey urged ministers to publish the document.
Labour MP Mr Healey said: "This is the second legal direction to the government to release the risk register.
"The judgment backs the public's right to know about the risks the Government is taking with its NHS plans. It gives strong legal support to a full and open debate about the NHS reorganisation.
"Ministers must now respect the law, release the risk register in full and let people make up their own minds on the NHS changes.
"Today's legal judgment must put an end to the Government's efforts to keep this information secret. They have dragged out this process for 15 months, while Parliament has been legislating for their NHS plans."
Mr Healey called for the information to be released before the Health and Social Care Bill completes its troubled passage through Parliament.
He said: "It's near the end of the eleventh hour for the NHS bill and Parliament rightly expects this information before it takes the final irrevocable step to pass the legislation.
"The Government could appeal, and prolong this legal row. But I call on the Prime Minister to accept today's court verdict and order the Department of Health to publish the risk register immediately."
The tribunal allowed the department's appeal against the release of a broader "strategic" register, covering officials' assessments of wider risks.
The full judgment with detailed reasons will be released "in the near future", the tribunal said.
A spokesman for the Information Commissioner's Officer said: "We welcome the decision of the tribunal to uphold the commissioner's decision notice ordering disclosure of the transitional risk register.
"We will consider the full details of the tribunal's decision once it has been made available."
A Department of Health spokesman said: "We are still awaiting the detailed reasoning behind this decision.
"Once we have been able to examine the judgment we will work with colleagues across Government and decide next steps."
The decision comes as the Bill enters the final stages of its protracted journey through Parliament.
The legislation was "paused" in the face of fierce criticism from Liberal Democrats and extensively rewritten.
Health Secretary Andrew Lansley has seen a range of medical Royal Colleges and unions come out against the reforms but the Bill has almost completed its progress through the Lords, having already cleared the Commons.