Anti-fracking campaigners have been given High Court permission to challenge a decision to allow further drilling in Balcombe.
A judicial review will take place later this year into the West Sussex County Council decision to grant planning permission to Cuadrilla for work at Lower Stumble.
It is the latest development in a legal battle against unconventional oil and gas testing led by Frack Free Balcombe Residents Association (FFBRA).
Cuadrilla was granted permission in May 2014 to return to the site to test for oil and shale gas.
Permission was for exploration of a "hydrocarbon lateral borehole" together with a new 14 metre high flare on the site.
The application received 889 objections and nine in support but permission was granted.
Legal firm Leigh Day, representing the residents, initiated a judicial review citing several objections and unsatisfactory communications with Cuadrilla.
It is alleged Cuadrilla's conduct at Balcombe has been “unlawful” with claims of non-compliance.
Campaign chairman Charles Metcalfe said: “This is brilliant news for the Frack Free Balcombe Residents Association.
“We and our lawyers Leigh Day have worked very hard to challenge the legality of WSCC's planning permission to Cuadrilla.
“Unconventional Gas and Oil exploration is dangerous, dirty and the wrong path to take."
Ugo Hayter of Leigh Day added: “We believe this planning permission has been granted unlawfully and flies in the face of overwhelming community opposition.”
A Cuadrilla spokesman said: "We are aware of the High Court's decision to grant a judicial review concerning West Sussex County Council's decision to grant planning permission for Cuadrilla to conduct a seven-day flow-test of the well at Balcombe.
“We will await the County Council's response.”