The Supreme Court has ruled that Surrey County Council should have considered the climate impacts of burning oil drilled from new wells in Horley.

Under planning law the assumption has always been that only the impacts from constructing the wells and not the use of the final oil products should be considered.

The case brought by Sarah Finch, on behalf of campaigners, could threaten new UK fossil fuels projects.

The council said it followed planning law.

Today’s judgement relates to the Horse Hill oil well in Surrey. The site was given planning permission to expand its operations in 2019, a decision that was challenged by a local resident, Sarah Finch, on behalf of Weald Action Group.

Lawyers acting for Ms Finch said that as part of the Environmental Impact Assessment the council should have considered not just the greenhouse gas emissions from building the wells but also burning any oil that was then used – known as downstream emissions.

The six wells at Horse Hill are expected to produce 3.3 million tonnes of crude oil over the next 20 years. Burning that oil would produce over 10 million tonnes of CO2 the environmental campaigning organisation Friends of the Earth has estimated.

The judgement – by a three-to-two majority – is likely to have a significant impact on decisions on future fossil fuel projects in the UK.

Campaigners claim the judgement could also effect ongoing legal challenges of new projects in the UK including Rosebank oil field and the proposed coal mine in Whitehaven in Cumbria too.

Because the UK law on environmental assessments is based in part on European law the ruling could have impacts abroad as well, they say.