The leader of the Nauru opposition grouping, Baron Waqa, says the caretaker Government is abusing the state of emergency powers and that's why they've taken the matter to court.
Legal action began today after Nauru's newly appointed judge John Von Doussa flew in from Australia, accompanied by the Opposition's two lawyers.
The Government of Marcus Stephen brought in the emergency regulations in June after months of political stalemate in the 18 member Parliament.
It's maintained the powers are legitimate and are needed to run the country.
But Mr Waqa says they want the court to resolve the issue once and for all.
"Our constitution only allows only 21 days to have anything that we consider critical to be attended to. We are given 21 days to have that done. But now we have lost count about how many states of emergency have been renewed. We are not happy about that."