The Corrections department is making no apologies for a five fold increase in its use of handcuffs on prisoners. They were used almost a thousand times in the 2016/17 year compared to just 183 times eight years ago. UN standards for prisoners, known as the Nelson Mandela rules, call for restraints to be used as a last resort. Correction's head Ray Smith told RNZ reporter Phil Pennington he needs to protect staff from increasingly violent inmates.