The FSA has been told to reveal the information which led it to wrongly slam Legal & General (L&G) with a hefty fine for endowment mis-selling.
In an appeal, the FSAs regulatory decisions committee found that L&G was not guilty of widespread mis-selling and said the FSA's £1.1m fine should be reduced.
At a hearing to discuss what fine L&G should pay the FSA was told to disclose how it reached the regulatory decision.
L&G argued that the committee's decision had been unreasonable and the FSA should pay its costs.
But the FSA said it was too late for additional disclosure.
Judge David Mackie ruling at the tribunal said before reaching a decision concerning fines he would like to see how the committee reached the decision to fine L&G.
He also ordered that information should be disclosed on 18 cases of alleged endowment mis-selling where fines were not given out.
