Vanuatu, one of the most vulnerable countries to global warming, is taking matters into its own hands.

After the world failed to boost targets for cutting emissions at last year’s climate summit, the volcanic atoll in the South Pacific is turning to international law to make sure countries live up to their commitments to curb greenhouse gases.

Vanuatu, leading a core group of 18 nations, wants the International Court of Justice to issue its assessment of what countries are obliged to do in order to make sure that global temperature rise is kept below the Paris Agreement target of 1.5 degrees Celsius. While those who breach their official pledges will not be taken to court directly, the ruling would be the most authoritative legal voice on where they are falling short both in terms of emissions cuts and finance to poorer nations.