'A Common Purpose', featuring the Australian Human Rights Centre's Associate Professor Andrea Durbach, has won the audience award for best documentary at the Sydney Film Festival.

The doco, which was a sell-out when it screened, shows the extraordinary story of Andrea's role in successfully defending 25 black South Africans in a capital murder trial under the Apartheid regime, and follows her recent return to South Africa to be reunited with her clients.

The film, directed by Mitzi Goldman, beat 38 competitors to take the people's prize.

If you missed the Festival screening, the documentary will be shown as part of Andrea's Professorial Lecture at the Faculty of Law on 18 August.

The story is also recounted in Andrea's book 'A Common Purpose - The Story of the Upington 25'.

Watch a preview of the film here.

For more on the award, go to the Sydney Film Festival website.