Australia's detention of asylum seekers has again spiralled out of control, with riots on Manus Island following last year's on Nauru. The violence is an inevitable response to the cruel and illegal detention of desperate refugees. Detention has long been the norm in Australia too. But this week the Abbott government quietly confirmed its very worst form - indefinite detention of recognised refugees.

This week the Abbott government failed to release more than 50 refugees indefinitely detained - from Villawood in Sydney to Maribyrnong in Melbourne - because of ASIO security assessments, as requested by the United Nations. Most of them have been locked up without charge or court order for four to five years.

Last year the United Nation's highest human rights tribunal found that Australia was illegally detaining the refugees, denying them judicial protection and the right to know the case against them, and treating them in a cruel, inhuman and degrading manner.

The UN accepted that detention was making people mentally ill, destroying families and children, and was not necessary for security. Five of the refugees have even attempted suicide, by hanging, electrocution, poisoning, or cutting, too traumatised to go on. No one deserves to live like that, without hope, life ebbing away behind the razor wire.

In total the UN found around 150 violations of international law. These laws were not imposed by foreigners, but were freely accepted by Australia as a party to an international treaty.

In ignoring the UN deadline, the Abbott government has confirmed that it is a lawless enemy of liberty and fairness, in lock step with its Labor predecessor. Last week, both major parties also supported a bill to make ASIO security assessments even harder to challenge.

We should not release the refugees just because the UN says so, or we're breaking our promise to the world, or it damages our global reputation, or it signals to other countries that it's OK to violate human rights.

We should release the refugees because disappearing people into the black hole of indefinite detention without charge or evidence offends the basic Australian values of liberty, fairness and the rule of law. It also does immeasurable human harm to those who have a right, as refugees, to our protection.

Freedom from arbitrary detention by the state is fundamental to all other rights, democracy and the rule of law. Liberty has been part of our culture since the Magna Carta 800 years ago. It is a precious value shared by all conservatives and progressives who care to control state power.

Without it, the state can lock you up forever without reasons or protection by the courts. The courts become a hollow shell, powerless to control bureaucrats and politicians, or hold the state to account. The executive becomes omnipotent and above the law. ASIO becomes judge, jury and executioner. Bad decisions become untouchable. The rule of law vanishes.

Arbitrary, illegal detention is also unnecessary to make us safe. We know this because we do not indefinitely detain Australians who are suspected of being dangerous. Instead we prosecute them in a fair trial before an independent court. Or we put them under surveillance, or impose an anti-terrorism control order. There is no reason to treat refugees differently. Only Australia, and America at Guantanamo Bay, maintain indefinite detention without charge.

Other democracies also do not deny a fair hearing. Instead, they balance security concerns against basic fairness. State secrets are still protected, but a person is never left wondering what they might have done to deserve losing their freedom.

Our paranoid, security extremism is un-Australian. It is un-Australian to forever disappear fellow human beings into immigration gulags, hopeless places which destroy people's minds. It is un-Australian to damage refugee children and families and to treat the freedom of others as nothing.

Indefinite detention is the convenient solution of timid parliaments and governments too easily spooked by the ghost of national security, too spineless to stand for liberty and fairness, and too fearful to do what is right.

Why is our freedom-loving Attorney-General silent? Senator Brandis says he opposes a "narrow and selective" view of rights and wants to "restore balance". Why then, does he passionately defend the boutique freedom of an elite media columnist, Andrew Bolt, to denigrate Aborigines, but not condemn the more destructive harms of indefinite detention and inhuman treatment?

His inspiration, the liberal philosopher John Stuart Mill, would be turning in his grave at these laws. Why can other "decision-makers in the real world", as Senator Brandis regards himself, like the conservative British government, respect rights while protecting security, but he can't? Or isn't he genuine about reclaiming liberty for the Liberal Party? Why is a conservative government so against liberty and so in favour or arbitrary, absolute state power?

Indefinite detention is not wrong because of a treaty or the UN. It is wrong because it is alien to Australian values. Australia should be a place of liberty not gulags, fairness not faceless security officers, empathy not cruelty, and courage not fear. We are better than this.

Ben Saul is Professor of International Law at the University of Sydney, and represented 51 refugees in their UN cases.