East Renfrewshire Council has lodged a petition with the Court of Session in Edinburgh seeking approval to build a new £24 million Barrhead High School on Cowan Park in the town.
Representatives of the Cowan Park Action Group have taken legal advice over contesting the council's land-grab on the town's biggest green space.
The council said the petition was necessary to release the land from 'common good' to allow the school to be built.
The council plan involves demolishing the existing school adjacent to the park and building a new school on football pitches. The council says it will then turn the original school into a green space.
It says the proposed plan will take up to 37% less space in the park than the existing layout.
It is hoped the court action will help end the debate over whether or not it is legal to build in the park.
Objectors have 21 days to write to the court.