Greece's top administrative court ruled Friday that a weekend referendum asking voters whether or not they support bailout conditions can go ahead, rejecting a challenge by two individuals.
The petitioners -- one of them a former judge on the Council of State that decided the case -- had argued the plebiscite violated the constitution by asking citizens to decide a "public finances" question.
Their challenge had also insisted the question was couched in technical language which could confuse voters.
Prime Minister Alexis Tsipras is urging Greeks to vote 'No' in the referendum and thereby reject austerity measures demanded by international creditors.
Opposition parties including the centre-right New Democracy are campaigning for a 'Yes' vote, fearing that Greece could crash out of the euro otherwise.
The former judge who co-presented the petition to the Council of State on Wednesday was reported by Greek media to have ties to New Democracy.