Natfhe has issued a legal challenge to education secretary Gillian Shephard, claiming she may be exceeding her powers by attempting to reform early retirement regulations.
Natfhe solicitor Michael Scott wrote to Mrs Shephard on Monday. He explained that Natfhe would seek a judicial review if she does not respond by next Friday. The union is preparing an affidavit in anticipation of seeking leave for a judicial review.
Natfhe has obtained counsel's opinion that her proposal to transfer liability for early retirement costs from the Teachers Superannuation Scheme to employers exceeds her ministerial powers.
Specifically, the union claims that the 1972 Superannuation Act forbids the transfer of cost liability to an employer. Mr Scott said that by reducing TSS contributions to early retirements and expecting employers - schools, colleges and new universities - to make up the difference, Mrs Shephard was breaching provisions in the acts.
John Akker, Natfhe general secretary, said: "It is extraordinary that Mrs Shephard has misunderstood her powers on this matter. She is asking employers to find the funds for a scheme for which they have never received any contributions, while their employees have paid into the TSS for years."
The Government's proposed TSS reform has generated a storm of protest from the unions and vice chancellors of new universities, who say it will make early retirements prohibitively expensive and so less widely available.
This is the second legal challenge faced by the Government. The Association of Teachers and Lecturers had sought judicial review of the Government's attempt to stop a flood of early retirements before April 1 when the changes were to take effect. This challenge forced Mrs Shephard to make clarifications and, the ATL dropped its action. The implementation of the early retirement changes has since been postponed until September 1.
The Department for Education and Employment declined to comment on the Natfhe challenge until it had studied Mr Scott's letter.