The cabinet minister whose brother faces serious charges will not be stood down until the case is resolved, Prime Minister John Key says.
The minister told Mr Key's office of the matter three or four weeks ago.
Labour Party leader Andrew Little said Prime Minister should have immediately stood down the minister, if it was apparent there was a conflict of interest.
Mr Key said there was no conflict of interest and advice he received made it clear ministers were not accountable and should not have to stand down over the conduct of members of their families.
"A minister shouldn't actually just step down because one of their family members has an issue that they're dealing with, providing that there wasn't a conflict prior to that point and any potential conflicts are managed," he said.
"There will always be people who might be able to claim that case, but we work on the best advice we can get, and the best advice supports the stance I've taken, in line with the cabinet manual."
"In this situation, there wasn't one prior and ... the latter point can be managed."
Mr Key said there had been no changes in ministerial delegations.
Mr Little said this was a judgement issue that went to the heart of Mr Key's leadership.