National Anti-Corruption Commissioner Justice Paul Brereton has been found to have engaged in misconduct when he involved himself in proceedings that rejected further investigation into the senior public servant in the robo-debt scandal, who was an army reserve colleague.

The embarrassing finding came after the NACC’s independent inspector Gail Furness found Mr Brereton should have excluded himself completely from the decision not to investigate referrals from the robo-debt royal commission.