Mark Lundy's case has again reached the Supreme Court, where he is challenging his convictions for murdering his wife and daughter.
Lundy was previously convicted of killing wife Christine 38, and 7-year-old daughter Amber at their Palmerston North home in August 2000.
The latest in a long string of appeals will focus on "novel and junk science" used to analyse brain tissue at the scene, which Lundy's lawyer criticised in an earlier hearing.
Lawyer Jonathan Eaton, QC, said Lundy referred to himself as being a "guinea pig through the justice system".
The method for analysing the brain tissue had "never been used before, never been used again", and the evidence based off it had been found inadmissible by an earlier court ruling.