Kuwait's appeals court ruled Sunday that a government decision to raise petrol prices was in line with the constitution, overturning a decision by a lower court.
It said the decision to raise prices was within the cabinet's powers.
Ali al-Ali, one of several lawyers who filed the suit against the government, said on Twitter the group intends to challenge the latest ruling in Kuwait's supreme court, whose decisions are final.
Like other Gulf states that are heavily dependent on oil revenues, Kuwait has been hit hard by a sharp drop in crude prices since June 2014.
The Opec member recorded a budget shortfall of $15 billion in the fiscal year to March 2016.
It was the first deficit since the fiscal year to March 1999.