Parents of children at Hermon primary school went to the High Court in London last week to stop an attempt by the Welsh Assembly government to overturn their right to a judicial review of the case, which was granted in April.
The Welsh Assembly had approved the county council's closure plans, which are part of a proposal to merge three schools on one site and reduce surplus places.
At the High Court, barrister Gerald Clarke told Mr Justice Wilson that any legal move against the Welsh Assembly should have been made when it gave the green light to the scheme in January this year - and called for the case to be thrown out.
But, after listening to legal argument, Mr Justice Wilson gave permission for the challenge to go ahead.
The judicial review hearing will take place at the High Court in Cardiff over three days, starting on July 12. Nicholas Bowen, the parents' barrister, is arguing that the council's decision - and the approval of the Assembly - were unlawful and irrational, and that the council operated an "inflexible policy" in deciding to close the over-subscribed 50-pupil school.