A former Victorian Supreme Court judge says proposed new powers for security guards at detention centres would allow them "to beat asylum seekers in detention to death" with impunity.

In his submission of evidence to Senate hearings on changes to Australia's Migration Act, Stephen Charles SC said proposed amendments would make it harder to bring legal action against a guard who inflicted harm, and may even encourage it.

"The way I put it was that the guards were authorised to beat asylum seekers in detention centres to death," he told the ABC's PM program.

"Guards in detention centres will feel freer to exercise force, to use force against detainees on the ground that they've been told that they can do so where they think there is reasonable necessity."

The Senate hearing is considering new laws designed to keep order at detention centres.

Space to play or pause, M to mute, left and right arrows to seek, up and down arrows for volume. Listen Duration: 3 minutes 18 seconds 3 m 18 s Former judge says new powers will allow asylum seekers to be beaten to death ( Sarah Farnsworth ) Download 6.1 MB

It follows the release of the long-awaited Moss review, which highlighted allegations of sexual and physical assault on asylum seekers, including children, at the Nauru centre.

Mr Charles said he also provided evidence that under the changes, officers would get a greater level of immunity than was given to police right across Australia, and less training.

"The impression all of us had in giving evidence was that would get them something like a fortnight's qualification, which would be hopelessly inadequate," he said.

He said he told the Senate hearing the new powers were "a joke in extremely bad taste".

"I myself think that the amendments should be completely canned and they should start again from scratch," he said.

Australian Human Rights Commission president Gillian Triggs also spoke out against the proposed changes, saying it would become virtually impossible to bring legal action if guards did turn violent.

Ms Triggs said she recognised there may be occasions where private contractors would have to use force against people in detention, but took issue with the extent of powers the new bill would give them.

Australian Human Rights Commission president Gillian Triggs has spoken out against proposed changes to the Migration Act. ( AAP: Alan Porritt )

"Contracted detention service providers, for practical purposes, the Serco guards, are not police officers," she told the hearing.

"They should not be given wider powers or greater discretion. And there should be clearly defined limits to the power of contractors to use force."

Ms Triggs said the department's policy guidelines over the use of force were already clear.

"Force should be a measure of last resort, it should be used only for the shortest amount of time necessary, it should never be cruel, inhuman or degrading," she said.

"It should not be a punishment for that, of course, is a judicial and not an executive power, and it must not be excessive."

Ms Triggs said the language of the bill needed to be tightened up.

"If the power to use force is to be set out in the Migration Act then it seems to us particularly appropriate that the limits on that power should also be in the act itself, rather than confined to a policy document," she said.