There are fears on Nauru that the highest level of the judiciary will lose its independence if the country drops the Australian High Court as its final court of appeal.
Nauru is beginning celebrations of 50 years of independence and President Baron Waqa has said ending access to the Australian High Court is now appropriate.
But this comes amid a long running legal battle over an anti-government protest in 2015 which involves an appeal to the Australian court over sentences handed down by the Nauru Supreme Court.
An opposition MP, Riddell Akua, said he was concerned at the impact such a change would have.
"The high court of appeal will not be independent anymore. I feel that that needs to remain totally independent of the political influence that sometimes does happen."
Riddell Akua said the change could affect the 19 people, including a former president, still facing charges over the protest.
He said with just four opposition MPs in the 19 member parliament they have no chance of stopping legislation.