How effective is the system for investigating miscarriages of justice in England and Wales? Critics say the Criminal Cases Review Commission, the body charged with examining potential wrongful convictions, lacks teeth and needs to be thoroughly reformed. Are they right? Allan Urry examines cases in which prisoners, campaigners and lawyers say the CCRC doesn't do enough for those who continue to protest their innocence. Should the Commission be making more use of the latest DNA techniques to re-examine verdicts which relied on circumstantial evidence? And why did the CCRC twice refuse to pursue the case of a man who spent 17 years in prison for a serious sex crime he didn't commit? Producer: Rob Cave.