Changes to the constitution to include stronger free speech and press freedom protections are under consideration by a Senate committee after a proposal by independent senator Rex Patrick was put forward.

The proposed changes would place "a constitutional brake" on any legislative efforts to suppress freedom of expression, the bill's explanatory memorandum said.

But the Human Rights Law Centre would like to also see a human rights charter introduced.

As the only liberal democracy in the world without one, senior lawyer Kieran Pender said it was time a national set of guidelines were brought in to remove any ambiguity.

A number of national security laws passed over recent years had limited freedoms and were a concerning development for journalists and whistleblowers, he said.

"In recent years, we have seen a range of concerning secrecy and surveillance laws threaten public interest journalism and whistleblowing," Mr Pender said.

"Whistleblowers who have exposed serious wrongdoing have been prosecuted, and Australian media outlets and journalists have been raided.

"These events have revealed the fragility of free speech and free press in Australia and the urgent need for considered law reform to protect these core elements of our democracy."

Australia's position in the World Press Freedom Index has already slipped six places to 25^th in the past three years just below Namibia, Samoa and Latvia, he said.

It comes as an academic report released by progressive activist group Get Up earlier this week showed nearly 100 national security laws had passed in the past two decades.

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New social media takeover powers introduced last month granted to federal police have also been criticised for their broad approach.

The laws allow authorities to intercept messaging between suspected criminals but its application has been deemed too broad and intrusive by human rights and privacy experts.

The government also needed to urgently improve its whistleblower laws after first being handed a review with 33 recommendations nearly five years ago, Mr Pender said.

A number of major scandals, including the Brereton inquiry's findings and promises to look into the East Timor spying saga, had only been brought to light after disclosures.

"Australians have a right to know what the government is doing in their name, journalists have a right to do their jobs without fear of prosecution, and whistleblowers have a right to protection under the law," he said.

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