Former High Court Judge and same-sex marriage advocate Michael Kirby says he will have no part in the postal ballot on whether to change marriage laws.

Key points: Approach out of step with changes to rights for Aboriginal people, women's rights or dismantling White Australia Policy, Kirby says

Approach out of step with changes to rights for Aboriginal people, women's rights or dismantling White Australia Policy, Kirby says Hinch, Laming urge people not to boycott vote, despite its flaws

Hinch, Laming urge people not to boycott vote, despite its flaws Poll should be extended to Australians under 18, Dastyari argues

"I feel as a citizen that I'm not being respected. I do feel that this is an improvisation which is completely irregular," he told RN Breakfast today.

"It's just a complete political improvisation and it's completely unacceptable and it should stop. And I feel as a citizen I'm being treated in a second-class way by interposing an arrangement of this kind between the making of the law in Parliament, which is where it should be done."

Mr Kirby said other changes in Australia had not been made by postal ballot or plebiscite.

"It wasn't done in the case the advancement of the legal rights, equal rights of the Aboriginal people, it wasn't done in respect of women's advancement of legal rights, nor in the demolition of 'White Australia'," Mr Kirby said.

'They should abandon it'

He criticised the Government's move to proceed with a postal ballot when Parliament rejected the bid to have a compulsory plebiscite.

"What has happened is, the Parliament of Australia has spoken. It has said it does not want a plebiscite.

"Parties can have their platforms but when the Parliament of the nation speaks … unless you're totally disrespecting the Parliament, and unless you just don't care what people say and do and the votes that are taken in Parliament, parties will adjust what they've said before.

"This is a disrespect of the Parliament of the nation where our laws are made."

Mr Kirby supports same-sex marriage but said he would not advocate for it in this process.

"I think the less said about this irregular and unscientific polling the better. I'm not going to take any part in it whatsoever," he said.

"I think they should abandon it."

However, Prime Minister Malcolm Turnbull urged people not to boycott the postal ballot on the "important decision".

"We encourage every Australian to exercise their right to vote on this matter, it's an important question," he said.

"Everyone will have an opportunity to have their say, we encourage everyone to have their say."

Hinch says vote is 'rubbish' but urges against boycott

Crossbench senator Derryn Hinch dismissed the postal vote but urged people not to boycott.

"The postal vote is rubbish … I hope they don't boycott," he said.

Senator Hinch also criticised former prime minister Tony Abbott, who yesterday said people should vote no in the ballot if they wanted to support free speech and take a stand against "political correctness".

"I think Tony Abbott's comments yesterday were atrocious," he said.

"[What] two people in love who want to get married has to do with freedom of speech I have no idea."

Liberal backbencher Andrew Laming said a boycott would be "massively disappointing — it is an indication clearly that the yes campaign feel that they cannot win a public vote".

Give 16-year-olds a say, Dastyari argues

Labor senator Sam Dastyari argued the postal ballot should be extended to younger Australians.

"Why is this being limited to people above 18 if this is a non-binding poll? Why aren't 16 and 17-year-old Australians also being enfranchised in this process?" Senator Dastyari asked.

He also called the postal process "so last century it is mind-boggling".

"Why aren't we allowing online voting?

"This is a bad idea, it is not a good way of dealing with it, but there are simple steps to at least try and enfranchise some young Australians."