According to the British, the settlement of Tasmania involved the takeover of unsettled land which the Aboriginals, as savages, had no claim to. The British believed that civilised people built structures and utilised the land, and that they were of the Christian faith.
Because the settlement was considered to involve land possessed by the British through discovery rather than conquest the Aboriginals automatically became British subjects. Had this also involved British citizenship then perhaps there would not have been such devastating impacts on the Aboriginals, however, from the onset they were not afforded any of the rights of British citizenship. As they were considered to be savages they had no rights to their land or land ownership - any attempts they made to defend what for centuries had been theirs was considered criminal in intent under British law.
In one instance two Aboriginals were hung for the murders of around 5 settlers. Whilst there was no question of their guilt it is interesting to note that during the trial they were unable to give evidence to protect themselves or plead for a lesser sentence because they were not Christian.