A tribunal of Papua New Guinea judges will rule this week on whether a constitutional challenge to the Australian-run detention centre on Manus island should be dismissed in its current form.
But lawyers for opposition leader Belden Namah say they will bring the case again if the court strikes down their bid.
It has been four months since Mr Namah challenged the constitutional authority of the PNG government to open the centre.
The case has been bogged down in procedure ever since, as lawyers argue over the legal method under which the challenge was first brought.
Lawyers representing the government have argued Mr Namah did not fulfil all the proper criteria under PNG's Supreme Court rules.
The state's lawyer, Ian Molloy also told the court that the case raised issues that were not covered under section 18.1 of PNG's constitution, which in part sets out the jurisdiction of the Supreme Court.
Mr Namah's lawyer Loani Henao says he welcomes any decision from the courts because it will provide direction after months of procedural log-jam.
