Police will be able to call on Australia’s military assets more easily during unfolding terror attacks under changes to the Defence Act that will hit the parliament today.

The laws were flagged last year following a Turnbull government review of defence powers, triggered by the Lindt Café siege in 2014.

While police already have the power to call on the Australian Defence Force during domestic terror attacks, the officers must only do so when their own capabilities have been exceeded.

READ MORE New powder restrictions to hit travellers at Australian airports

The new laws will set a lower threshold that will allow various ADF units to be called on when police believe the military have "specific assets, skills or personnel" that would help deal with the attack, Attorney-General Christian Porter said.

“In a long siege-type situation, it may be that the SAS or Commando regiments would have particular skills that could assist and help save Australian lives,” Mr Porter said.

Those elite special forces soldiers would rarely be able to respond to unsophisticated attacks using weapons like knives, which are usually over very quickly.

But Mr Porter said military assests could be useful in sieges, in complex multi-stage attacks like the one in Paris, or those using chemical or biological weapons.

"Ultimately, what we couldn't let persist is a situation where serious skills and personnel available inside the ADF were always going to end up being left in the shed, where they could be deployed to save Australian lives," he told reporters at Parliament House on Thursday.

State police would still be the first responders and would be responsible for the decision to call in the troops. Senior ministers and the governor general will also need to give approval.

"This will be a very heavily scrutinised process. You will not get call out unless it is utterly appropriate," Mr Porter said.

The wording of the laws will be revealed when the bill is introduced to the parliament on Thursday.

But Mr Porter said the laws would not be specific to just terror attacks, and could apply to violent riots. The laws will borrow language from the Constitution that refers to "domestic violence" - meaning violence within Australia.

Asked why the government did not make the laws specific to just terror attacks, Mr Porter said there would be difficulties in "distinguishing between one type of violence and another", especially in an unfolding terror attack.

"It's something that a terrorist could very easily use as a cover for events. So for instance in the Paris attacks, in the very early stages, it was quite unclear what was going on," he said.

Labor, by convention, almost always offers bipartisan support on national security matters.

Announcing the laws back in July last year, the government said the states would be encouraged to give police more legal protections so they felt empowered to shoot and kill terrorists.

The Australian Strategic Policy Institute's Peter Jennings told SBS News police culture was already shifting away from prioritising arrests since the Lindt siege in Sydney.

“Increasingly, because of what they call this active-shooter problem, police are basically training to kill terrorists on the spot. And in that sense, on that particular area, their culture is becoming more like the military culture,” Mr Jennings said at the time.

Mr Porter said soldiers would be bound by the same use-of-force rules as police when attending domestic terror attacks.

"There are very well known rules with respect to the use of lethal force ... it cannot be exacted by police force personnel unless they consider that there is a reasonable prospect that that is necessary to save someone's life or prevent serious injury for a civilian."

ADF soldiers would not be allowed to make arrests or gather evidence, but could stop, detain and take weapons off people.