The division between Islamic and secular laws will be put to the test in the Indonesian province of Aceh, as the treason trial of five pro-separatist negotiators continues next week. The lawyer representing the men says his clients will claim that, as Acehnese nationalists, they only recognise provincial Islamic laws, and not those of the Indonesian state. The controversy looks set to heighten, as the accused seem determined to challenge Indonesian rule in Aceh through the courts.

Presenter/Interviewer: James Panichi

Speakers: Adnan Buyung Nasution, lawyer; Associate Professor Tim Lindsey, Director of the Asian Law Centre, University of Melbourne

Panichi: Human rights lawyer Adnan Buyung Nasution says the charges brought against his clients – which range from treason to supporting acts of terrorism and "sinister conspiracies" – are ridiculous. He says the men are academics, farmers and businessmen who had simply volunteered to help out with the Tokyo peace talks, which collapsed shortly after their arrest.

Nasution: "They were appointed as representatives of the GAM, participating in the negotiations, in which the Indonesian government accepted them. "So why the, in a sudden, when the negotiations failed, they were arrested and prosecuted? It's a very strange case to me."

Panichi: The trial, which is scheduled to wind up at the end of October, comes at a particularly delicate time for the troubled province. This week, a high-level Acehnese secessionist rebel and his wife were killed, in what the Indonesian army has described as a gun-battle with the military. Teungku Jaelani is the first rebel leader to be killed since a major military offensive against GAM began in May.

And according to Dr Nasution, the army's presence in a province which remains under Marshall law has created a climate of fear, in which his clients can't be guaranteed a fair trial.

But in what may be an attempt to harness local support, Dr Nasution has announced that as secessionists, the five men don't recognise Indonesian laws, and will call for the trial to be scrapped.

Nasution: "The defendants are of the opinion that Aceh people are free people who never joined the Republic of Indonesia, because they have been always a free, independent and sovereign country of Aceh."

Panichi: So, does that mean they don't accept the sovereignty of the Indonesian court in Aceh?

Nasution: "Implicitly, you are correct. If they don't recognise or accept the sovereignty of the republic, automatically they should reject – make and exception, we call it, and objection – the authority of the court. But there has been nobody there to reject that suggestion."

Panichi: But is that realistic? Is the Indonesian government likely to accept that point of view?

Nasution: "Certainly not. Because, from the perception of the Republic, and I think all Indonesian people, when we proclaimed independence against the Dutch, against the Japanese, that covered already the Aceh people. In fact, during the revolution, the Aceh people supported the Republic. But those defendants say that it was only individuals who supported the republic, and not the whole people."

Panichi: Dr Adnan Nasution, who has just returned to Jakarta from Acehnese capital, Banda Aceh.

But according to some observers, the move is purely political, and has no chance of succeeding under Indonesian law. Associate Professor Tim Lindsey is Director of the Asian Law Centre at the University of Melbourne.

Lindsey: "It is true that Islamic law does apply to a broader extent in Aceh than in does anywhere else in Indonesia. This is because of powers granted under regional decentralisation laws by the Indonesian parliament in Jakarta to the provincial government in Aceh. And the powers include an ability to make laws in relation to Islam, as regional regulations.

"And they've done this. They've created an Islamic court, and there are Islamic codes. But these will never override a statue produced by the Indonesian government. There's a hierarchy of laws which applies throughout the republic, and these make it clear that regional regulations are always overruled by national statutes.

Panichi: Well, in that case, how will the courts deal with this claim?

Lindsey: "Well, the courts will simply apply Indonesian law to Aceh, as a component part of the republic – despite the fact that there are military hostilities going on there. They will simply apply the law relating to treason and subversion, try them, and they will be found guilty."