A former secretary of justice in Nauru, David Lambourne, says passports cannot be withdrawn on the basis of alleged past conduct.
20 Nauruans who have been accused of involvement in an anti government protest last year have had their passports withdrawn.
Among them are three former MPs, including former president Sprent Dabwido, who is in urgent need of cardiac medical care that is not available in Nauru.
Mr Lambourne says while Justice Minister David Adeang does have the power to cancel passports, he cannot do it based on something someone might have done in the past.
"He would have to have concern that at some point in the future that former President Dabwido was going to pose a security risk to the people and the country of Nauru. It is not appropriate for a passport to be cancelled for alleged past conduct."
David Lambourne says it is just another blatant abuse of power by David Adeang and the Waqa Government in Nauru.