Marriage referendum 'unnecessary': Brandis

For a change, Attorney-General George Brandis and his Labor counterpart Mark Dreyfus agree on something: a referendum is not needed to resolve the question of same-sex marriage.

In fact it was "entirely unnecessary", Senator Brandis said, citing the same paragraph of a High Court judgement Mr Dreyfus used to make his argument earlier in the day.

"That is an unambiguous, a unanimous and a recent statement by the High Court that the marriage power as currently written is ample to provide the parliament with the power to legislate for same-sex marriage," the attorney told Sky News.

Fellow cabinet minister Scott Morrison floated the idea of holding a referendum on Wednesday night, something Senator Brandis said he only became aware of on Thursday morning.

"It's very important that as attorney-general I do remove some confusion that seems to have crept into this debate," he said.

"There is no doubt whatsoever that a referendum to amend the constitution is not necessary."

It could be an option to gauge public opinion on the matter by holding a non-binding plebiscite, he said.