The Abbott government has been unable to answer questions about how its changes to race hate laws will work, including whether the laws will apply to Holocaust deniers.
Prime Minister Tony Abbott and Attorney-General George Brandis could not say whether a case involving Holocaust denier Gerald Toben, who was forced by a judge to remove material from his website in 2002, would reach the same conclusion under the new laws.
Under the changes, it would no longer be an offence to ''offend, insult or humiliate'' someone because of their race or ethnicity. A provision against ''intimidating'' someone would remain and a clause against vilification has been added.
Labor's shadow attorney-general Mark Dreyfus has said the laws water down protections against racist speech and create exemptions for free speech that are so broad you can "drive a truck" through them.
Mr Abbott told Fairfax Radio on Wednesday that statements denying the Holocaust were "ridiculous, it's hurtful and it's wrong" but was unclear as to whether such comments would be illegal under the revised Racial Discrimination Act.
''Well in the end that would be for a court to determine,'' he said.
''And the fundamental point that I make is that the best antidote to folly is commonsense and the best way to refute a bad argument is with a good argument.''
Mr Abbott said that he was not a judge and decisions on what was appropriate would be left to legal authorities.
''What we're saying is that it is an offence to vilify an individual or group based on race and we have defined vilification as incitement to racial hatred,'' he said.
Senator Brandis told Radio National that racial vilification, which has been inserted into the Act under the proposed changes, ''would always capture the concept of Holocaust denial''.
But the Attorney-General could not guarantee Holocaust deniers who published their views would be forced to delete anti-Semitic material.
''I can't guarantee something because I don't know, we're talking about a hypothetical case that you're putting to me,'' he said.
''Toben as I understand his case wasn't involved in the public discussion of a matter he just put some nonsense on his website.''
Labor continued its attacks on the revised laws, after criticising on Tuesday the broadening of exemptions for freedom of speech. It will launch a blitz on Liberal-held marginal seats to warn migrant communities about the Abbott government's plans to water down race hate protections.
''It is a sad thing that one of the first priorities of this new government is to make it easier to racially abuse people,'' Deputy Opposition Leader Tanya Plibersek told Radio National on Wednesday.
''I am a great supporter of free speech, that's why I'm a great supporter of the ABC.
''And I noticed that this government whenever the ABC says something that the government doesn't like they're very quick to hop in and say it's not that the ABC should have the same right to free speech that they say they're defending with these legal changes.''
The elected representative body for Aboriginal and Torres Strait Islander peoples also issued a strongly worded statement condemning the government's proposed changes.
"We are horrified to consider the kind of Australia that could grow out of what is now being proposed," said Kirstie Parker, co-chair of the National Congress of Australia's First Peoples.
"We know intimately the impact that racist abuse has on our peoples. It... literally makes us sick."
Ms Parker said it was ''beyond comprehension'' that the Abbott government would ''openly champion a single commentator, Andrew Bolt'' in watering down the race hate laws.
There was little opposition to the reforms in the Coalition party room on Tuesday, although La Trobe MP Jason Wood, a former policeman, raised concerns that the broadness of the new definitions would make it virtually impossible to get a prosecution.
A number of Liberal MPs whose electorates have a high proportion of ethnic and overseas-born residents are known to be nervous about the potential backlash.
Indigenous Liberal MP Ken Wyatt, who last week threatened to cross the floor to oppose the change, said on Tuesday that he would consult with his community about the proposed changes.
Mr Abbott is facing opposition from the head of his indigenous advisory council Warren Mundine, who is urging Mr Abbott to drop the controversial plans, but he said he wouldn't walk away from the council in protest.
Mr Mundine, an indigenous leader and former national Labor president, said he copped racial abuse nearly every day.
''When you let people off the chain in regard to bigotry then you start having problems,'' he told ABC radio on Wednesday.
Mr Mundine said society made it quite clear that racism and bigotry were unacceptable. ''We have had conversations about it and our advice to the prime minister was that they should not be going down this track.''
Labelling the proposed changes the ''Andrew Bolt clause'', Greens leader Christine Milne said it would create a legal loophole to use offensive or inciteful language.
Independent senator Nick Xenophon said he would be talking to community groups to gauge their reaction, but Mr Mundine's opposition was worth noting.
''In a democratic country as ours you have a right to be a jerk and an idiot,'' he told reporters.
''But . . . anything that incites hatred, that could potentially incite people to violence, is something that we must as a society do everything we can to prevent.''
Scottish-born Labor senator Doug Cameron, who left his home country to escape bigotry, says Senator Brandis and the Coalition should have a good look at themselves.
''They obviously don't understand what bigotry does to individuals, what bigotry does to communities.''
with Jonathan Swan