An RAF lieutenant challenging the Ministry of Defence over the right to breastfeed her baby at work is to have her case reheard.
Helen Williams, 31, from Bristol, is to have a fresh hearing into her claim that the MoD sexually discriminated against her by making it impossible to breastfeed her baby daughter at work.
The ruling could affect thousands of women hoping to breastfeed once they return to work either by taking time out to feed their babies or to express milk.
An MoD spokeswoman said: "Servicewomen who wish to breastfeed their children are liable to undertake the full range of duties and it is only subject to local circumstances that they may be permitted to return to duty whilst still breastfeeding."
She added: "The decision by the employment appeal tribunal was to remit the breastfeeding issue to a fresh tribunal for a decision.
"That means that both Mrs Williams and the MoD have the opportunity to put their side of the case and to clarify the UK's legislation for all employers and employees."
Last year an employment tribunal decided that Mrs Williams, who gave birth in 2000, had been directly discriminated against on the basis of her sex over breastfeeding.
The order for a fresh hearing into her case has come after an appeal hearing brought by the MoD.