McDonald was one of the first eleven judges elected by the United Nations to serve on the Yugoslav Tribunal and went on to become its president between 1997 and 1999, the only woman to occupy the position since its founding in 1994.
As the presiding judge in Trial Chamber II, she issued the tribunal's verdict against Duško Tadic, the first international war crimes trial since the Nuremberg Trials and the International Military Tribunal for the Far East.
The Tadic case was also the first international war crimes trial involving charges of sexual violence.