The Governor-General has referred Scott Watson's murder convictions to the Court of Appeal.
Watson was convicted of the murders of Ben Smart and Olivia Hope in 1999 - their bodies have never been discovered.
The pair were last seen getting off a water taxi and onto a boat, which police would later say was Watson's home-built sloop, Blade.
Watson has always maintained his innocence. Police accused him of killing Smart and Hope on his yacht after a New Year's Eve party at Furneaux Lodge in the Marlborough Sounds.
Now, Justice Minister Andrew Little has advised Governor-General Dame Patsy Reddy to refer the convictions to the Court of Appeal for further consideration.
It comes after a former High Court Judge reviewed Watson's application for the royal prerogative of mercy.
"The Governor-General accepted my advice, and granted Mr Watson's application," Little said in a statement on Friday.
"As the matter will shortly come before the courts, I will not be making any further comment."
Initially, Watson's plea to the Court of Appeal in 2000 was unsuccessful, as was his bid for an appeal to the Privy Council.