A new barrier to climate action is opening up in an obscure and secretive part of international trade law which fossil fuel investors are using to sue countries if policy decisions go against them. We speak to experts about the investor-state dispute settlement (ISDS) mechanism and how it works. Many are worried that these clauses in international trade deals could jeopardise global efforts to save the climate – costing countries billions of dollars in the process.

Featuring Kyla Tienhaara, Canada research chair in economy and environment at Queen's University, Ontario in Canada, Emilia Onyema, reader in international commercial Law at SOAS, University of London in the UK, Lea Di Salvatore, PhD researcher at the University of Nottingham in the UK and Maria-Rita D'Orsogna, anti-oil activist and professor of mathematics at California State University, Northridge in the US.

This episode was produced by Gemma Ware and Mend Mariwany, with sound design by Eloise Stevens. Gemma Ware is the executive producer. Our theme music is by Neeta Sarl. Full credits for this episode are available here. A transcript is also available. Sign up here for a free daily newsletter from The Conversation.

Further reading:

• How treaties protecting fossil fuel investors could jeopardize global efforts to save the climate – and cost countries billions
• Energy charter treaty makes climate action nearly illegal in 52 countries – so how can we leave it?
• British investors could sue Australia over climate action if UK joins trans-Pacific trade pact