[2] Gearin was born in Sydney, New South Wales, in 1949 to Ellen (née Dempsey) and Alan Louvain Tait, She attended St Kevin's Primary School in Eastwood and Our Lady Of Mercy College, a Catholic boarding school at Parramatta.
In 1967 she was awarded a Commonwealth Scholarship to study law at the Australian National University in Canberra.
In 1986 the Northern Territory Attorney General's Department recruited Gearin, who was soon promoted to the role of senior litigation solicitor.
[3] The resulting book and recommendations contributed significantly to policy developments in the field, both in the Northern Territory and nationally.
[2] In the early 2000s she was the President of the NT Chapter of the International Commission of Jurists and was an official observer at the War Crimes Tribunal hearings in Dili in 2002.