The Terrorism Suppression Act, passed 2002 after September 11, 2001. Legislation has twice been amended, a third amendment bill is before parliament.

Why do we have them?

To meet our obligations to pass domestic laws giving effect to United Nations' resolutions against terrorism. These include taking steps to prevent terrorist recruitment and financing.

What is terrorism?

There's no common international definition of terrorism as it's difficult to get a definition that catches all that should be caught but excludes conduct most people intuitively believe should not be included. There's also the argument that one person's "terrorist" is another's "freedom-fighter".

Our act: a terrorist act is one intended to cause death or serious bodily injury, done to advance an ideological, political or religious cause, and intended to induce terror in a civilian population or "unduly compel" a government or international organisation to do or abstain from doing something. The definition includes not just the execution of a terrorist act, but also its planning and preparation.

While it is not an offence to simply belong to a terrorist group, it is an offence to participate in a so-called "designated entity" if this is done for the purpose of enhancing the group's ability to perform a terrorist act.

Charges may be laid under the Terrorism Suppression Act against individuals and/or organisations that are not designated entities.

What is a designated entity?

A specific person or organisation listed by the UN Security Council as a terrorist entity. Our legislation provides for such a list to be drawn up, with requests co-ordinated by police and given to the prime minister for official designation. The UN lists more than 500 international organisations and individuals but no New Zealand groups.

What are the penalties?

Up to 14 years' jail for participating, recruiting or financing. Up to seven years for dealing in property or harbouring/concealing a terrorist, and up to 10 years' jail, and/or a $500,000 fine, for receiving, possessing, using, transferring or altering nuclear material if the person knows the material is nuclear (or is reckless about the possibility) and it is used as the basis of threats or causes death, injury or disease.

What are the proposed changes to the act?

Terrorism financing: the act has significant protection for supporters of "liberation" movements (eg the ANC in South Africa or East Timorese resistance to Indonesian rule). Currently it's not an offence to finance activities "for the purpose of advocating democratic government or the protection of human rights". This clause is not in the bill before parliament.

Clauses relating to nuclear terrorism will be beefed up to comply with international obligations.

Committing a terrorist act: a new offence will be created. The maximum penalty will be life imprisonment.

Can the police arrest suspects under anti-terror laws?

Unlike Australia, the US and UK, NZ police have no special powers to arrest, detain or interrogate suspects, but can get a warrant to intercept communications to investigate people they believe are involved in terrorist acts. The attorney-general's consent is required.

Why is the law controversial?

Its critics say under the current wording, the law could be used against those engaging in political or industrial protest action, particularly if their actions are deemed to disrupt infrastructure facilities in a way that endangers human life.

The Public Issues Committee of the Auckland District Law Society says there are fundamental difficulties with the use of evidence, and fairness issues if the defence relies on classified information from overseas security agencies that it is not permitted to see in full, let alone subject to proper cross-examination. There is no proper judicial process to enable those deemed to be terrorists to clear names.

Is Australia's anti-terror law different?

Australia's most recent anti-terror laws (2005) are considerably more draconian. Suspects can be placed in preventative detention for up to 14 days without charges being laid or any evidence of criminal involvement. They can be interrogated by security services, but it's an offence for media, or anyone, to disclose an individual's been detained or interrogated.

"Control orders" (virtual house arrest without charge, let alone conviction) can be placed on suspects for up to a year. Suspects may be ordered to live where directed, stop working, to cease using the phone and internet and wear tracking devices. They will be encouraged to submit to "re-education". The imposition of control orders is based on "risk", not evidence.

Australia anti-terror law also significantly curtails the rights of citizens to express opinions the government doesn't like. There is no presumption of innocence for anyone arrested under this section of the law.