On behalf of 34,000 specialists and managers, Prospect said the Bill laid before parliament was vulnerable to challenge on three fronts – legal, constitutional and European.

Dai Hudd, Deputy General Secretary, said: “This Bill is unlawful and unnecessary. Prospect stands ready to enter negotiations on changes to the scheme at any time. But we will resist imposed changes in the final Bill that are unlawful and an abuse of ministerial power.”

Prospect says the Government’s emergency ‘money bill’ is unlawful because:

• it has the effect of changing the terms of the Civil Service Compensation Scheme by removing the accrued rights of civil servants, in breach of protection provided by the 1972 Superannuation Act
• money bills are only intended to be used for revenue-raising measures, not making amendments to other random pieces of legislation that should go through the full parliamentary process
• the removal of accrued rights would be in breach of Article 1 of the first Protocol of the European Convention on Human Rights, which protects individuals against the state depriving them of their possessions.

Dai Hudd said: “We have considered legal advice and can find no precedent that would support the use of a money bill for the purpose now intended by Government.

“We shall fight this measure in parliament, in the courts and in Europe. The Government should come to the negotiating table and agree arrangements that are fair to its staff and in line with the rest of the public sector.”

The Government intends to terminate the current CSCS terms and replace them with a cap of 12 months’ pay for compulsory redundancy compensation, and 15 months’ pay for voluntary redundancy. Prospect has proposed resuming negotiations with government on the basis of the deal agreed by five unions with the Cabinet Office five months ago.