Australians should be "alert and alarmed" about the erosion of their rights, Australian Human Rights Commission (AHRC) president Gillian Triggs has said.

Professor Triggs criticised politicians and the judiciary for failing to protect basic freedoms while delivering the Derek Fielding Memorial Lecture at Brisbane's Supreme Court on Wednesday night.

She said human rights concerns in Australia had reached "unprecedented" levels in the past few years.

Professor Triggs said it now lagged behind other countries on issues such as offshore detention, counter-terrorism laws and marriage equality, and that both parliament and the judiciary were to blame.

"Australia has become, in my view, isolated and exceptional in its approach to the protection of human rights," she said.

"Parliamentary representatives are ill-prepared for their traditional and crucial role as the bulwark against the overreach of executive government and as the protectors of fundamental freedoms.

"Respective parliaments have failed to protect the fundamental human freedoms in Australia, and our judges sadly have not taken up the challenge to strike down legislation that violates common law rights that are as ancient as the Magna Carta."

She said Australians should be "alert and alarmed" about the erosion of their rights.

Professor Triggs questioned why Australia's High Court had upheld offshore detention laws, when Papua New Guinea's judiciary had ruled it was unconstitutional.

She also criticised plans to hold a public, non-binding vote on same-sex marriage, where that right was protected by the United States constitution.

Professor Triggs also accused Federal Parliament of passing counter-terrorism laws that were "disproportionate to any legitimate aim to protect national security".

"Indeed Australia has been accused of hyper-legislating counter-terrorism laws, enacting far more such laws than comparable states like the United States and United Kingdom," she said.

Professor Triggs said it was a sad state of affairs given Australia was historically a global champion of human rights, and marked 2001 as a turning point.

"Then something went terribly wrong," she said.

"With the start of the new millennium, Australia faltered — we've been in retreat.

"And indeed the former bastion of support for fundamental freedoms has explicitly passed laws that violate our common law rights as well as international law."

She renewed calls for a federal bill or charter of rights to enshrine protections in law.