Thanks for your question Toby. The Australian Constitution does not recognise or mention Aboriginal and Torres Strait Australians. However there are 2 sections which have been used to make laws specifically for Aboriginal and Torres Strait Islander peoples. These are section 25 (races disqualified from voting) and section 51 (xxvi) (the Australian Parliament can make laws for any race).
Aboriginal and Torres Strait Islander peoples were excluded from the discussions about the creation of Australia and the drafting of the Constitution. Apart from some Aboriginal people in South Australia, the first peoples of Australia did not participate in the referendums in which the public agreed to the draft Constitution.
In 1967 the Australian people were asked in a referendum if the Constitution should be changed to remove section 127 which excluded Aboriginal and Torres Strait Australians from being counted in the census, and modified section 51 (xxvi) to allow the Parliament to make laws for Aboriginal and Torres Strait peoples. The referendum was agreed to with the largest yes vote ever recorded.
Recently there has been discussions that the Constitution should be changed again to remove sections 25 and 51 (xxvi) and/or include a preamble which recognises Aboriginal and Torres Strait peoples as the first Australians.