Senator Crossin has been dumped as Labor's top Senate candidate in the Northern Territory in favour of Aboriginal sportswoman Nova Peris, who the Prime Minister, Julia Gillard, anointed as the party's first indigenous federal parliamentarian.

Senator Brandis made the comment shortly before taking a submission from the National Congress of Australia's First Peoples and the National Aboriginal and Torres Strait Islander Legal Services on the draft anti-discrimination bill.

Senator Crossin, who is chairing the Senate inquiry, replied: ''I couldn't possibly comment, Senator Brandis.''

The comment capped a day of feisty interrogation of respondents to the bill by Senator Brandis.

He later told Gillian Triggs, the president of the Australian Human Rights Commission, that he thought the conservative columnist Andrew Bolt's comments on Aborigines, which were found by the Federal Court to have constituted racial vilification, were ''quite reasonable''.

Bolt was found by the Federal Court to have contravened the Racial Discrimination Act in newspaper columns that accused prominent light-skinned Aborigines of choosing to identify as black for personal gain. Senator Brandis made his comment in the context of arguing that it should not be illegal for people to express political opinions.

Professor Triggs said those types of comments would be protected by objective standards of reasonableness and the only cases that had reached court were ''particularly egregious''.

Professor Triggs, who had earlier criticised the new definition of discrimination, which extends to conduct that might offend, warned that it would be better to remove that clause than throw the laws out in their entirety.