Ineos is trying to win millions of pounds in damages by arguing the Scottish Government committed a misuse of ministerial power by enforcing the ban.
The firm is both challenging the legality of the decision and suing the Scottish Government for compensation for an alleged breach of its human rights.
However FoES has now submitted a public interest intervention in the Ineos judicial review - the first time such a challenge has been made on environmental grounds.
FoES argues that not only is the ban lawful but that the Scottish Government is required to ban fracking in order to meet Scotland’s legally binding climate change commitments.
FoES Head of Campaigns Mary Church said: “We are getting involved in INEOS’s judicial review of the fracking ban in order to put forward crucial climate change arguments in support of the ban that otherwise would not have been heard.
“Our intervention argues that the Scottish Government is required to ban fracking so as to urgently cut greenhouse gas emissions from fossil fuels, in line with legally binding climate targets.
“We are confident that the process to ban fracking was robust and fair, and we hope that the courts will find against INEOS.
“A two-year process looked at mountains of scientific evidence that spoke of the risks of the unconventional oil and gas industry to our environment, climate and people’s health.
“There is overwhelming support for the ban from communities on the frontline of this industry, people the length and breadth of Scotland, and almost all the parties at Holyrood.”
Friends of the Earth Scotland is represented by the Scottish law firm Balfour+Manson and Aidan O’Neill QC of Ampersand and Matrix Chambers, with input from Leigh Day in London.
The intervention will be through a written submission to the court , citing EU, Scottish and UK environmental law, national and international obligations on climate change, as well as the link between human rights and environmental protection.
Balfour+Manson solicitor Sindi Mules said: “Over 60,000 people engaged in the consultation on fracking before Ministers implemented the ban, with 99 per cent per cent opposed to the industry, demonstrating the tremendous importance of this case.
Leigh Day solicitor Carol Day said: “As far as we are aware, this is the first intervention in the Court of Session on environmental issues and one of only a handful to have been approved under the new Judicial Review rules”.