The Prime Minister's reluctant to overhaul the justice system, following the Roast Busters case, but says it's an issue the government will get advice on.

Critics say a less adversarial court system - and allowing the alleged victims to appeal the police decision not to prosecute - would help ensure justice is served.

John Key says if there's a better way forward, that's always worth exploring, but the justice system has to be fair to both sides.