Judges will have to reveal details of their financial interests if a bill that has passed its first reading becomes law.
The Government supported the Green Party's bill in parliament on Wednesday night and it went through on a unanimous vote.
But there's no guarantee the Government will back it through its later stages, and if it doesn't the bill will fail.
"This bill deals with a serious subject but we have reservations about whether a register of judges' pecuniary interests is an appropriate mechanism to safeguard public confidence," National MP Simon Bridges said.
"It has to be carefully considered by a select committee."
Green Party MPs said ministers and MPs already have to declare their financial interests every year and judges should have to do the same.
"They must be beyond reproach, a threshold of confidence must be enshrined," said Julie Genter.
The Parliamentary register covers assets held by MPs and the trusts they put their money in, but it doesn't show what they're worth.
The bill has been sent to the justice select committee for public submissions.
NZN