The fear of terrorism is leading the government to expand its executive powers, and legal experts are concerned.

Gillian Triggs has warned that governments are taking advantage of the fear caused by terrorism to create laws that are “out of proportion to the legitimate aim of protecting national security”.

She said that recent decisions like the postal survey on marriage equality and the creation of a super ministry of home security were examples of big decisions made without parliamentary approval.

“My concern is that an imbalance has crept into our democracy so that increasingly the courts are marginalised by legislation,” she said.

“Compliant parliaments, including oppositions over many years, have failed to exercise their historical restraint and pass laws that breach the rule of law. Executive cabinet government assumes ever more power.

“The result is that our democracy becomes weakened by the growing powers of the executive and by a corresponding diminution in the independence of the judiciary and a growing impotence of parliament.”

Dr Triggs says Australian courts are failing to consider international laws when making decisions, particularly relating to immigration.

She said the issues were compounded by Australia’s lack of a bill of rights.

“For all these reasons, in Australia we no longer speak the language of human rights and are increasingly out of step with comparable legal systems in the UK, Europe, Canada, the United states, even our cousins the New Zealanders,” she said.

Dr Triggs said governments are taking advantage of the fear of terrorism and unregulated migration to enact laws without a proper basis in evidence, which are disproportionate to legitimate purposes, breach fundamental freedoms and contravene the rule of law.

She said proponents of these laws use fear to avoid scrutiny.