The leader of the group opposed to Nauru's caretaker administration, Baron Waqa, says the appointment of a new judge to the Supreme Court has made it more likely that their case over the state of emergency can be heard.
The President Marcus Stephen has encouraged MPs who say the state of emergency is illegal, to take the matter up with the newly appointed judge Australian John Von Doussa.
Nauru has been in a political stalemate, ruled for the past three months by a caretaker government using emergency powers, which have been renewed until early October.
Supreme Court cases are now expected to start to be heard next month.
But Mr Waqa says their case is unlikely to come up until the state of emergency is lifted.
"Any case brought to the courts against the President over the legality of his orders will not be entertained until after the emergency powers, or state of emergency."