For more than 20 years, Franco-Senegalese lawyer Anta Guissé has worked for the defence at international tribunals for Rwanda and Cambodia, as well as the International Criminal Court. Now she has just pleaded for victims’ families in Burkina Faso in the trial on the assassination of former president Thomas Sankara, where the verdict is expected on April 6. She talks to us about how she sees such trials for “exceptional crimes”.