From the death penalty, to laws against homosexuality, Britain's criminal justice system has undergone momentous change in the last 70 years. In this Timewatch guide to Crime and Punishment, presenter Gabriel Weston examines how television has played a crucial role in documenting these seismic shifts in British law and policing. Looking back through the Timewatch back catalogue of documentaries and a host of BBC archive rarities, Gabriel discovers how historians and filmmakers have not only chronicled these profound changes in law but also managed to shape public opinion. By highlighting miscarriages of justice, like that of the wrongful imprisonment of the Birmingham Six, or by shining a spotlight on other issues of corruption and damning flaws in police procedures, Gabriel finds that television actually became a powerful agent for change.

• Alice Roberts